Q&A Hero

Q: The price of a bond is uniformly distributed between $80 and $85. a. What is the probability that the bond price will be at least $83?b. What is the probability that the bond price will be between $81 and $90?c. Determine the expected price of the bond.d. Compute the standard deviation for the bond price.

Q: A random variable x is uniformly distributed between 45 and 150. a. Determine the probability of x = 48.b. What is the probability of x 60?c. What is the probability of x 50?d. Determine the expected vale of x and its standard deviation.

Q: Refer to Exhibit 3-4. The variance isa. 6.969b. 7.071c. 48.570d. 50.000

Q: Identify the null and alternative hypotheses for the following problems.a. The manager of a restaurant believes that it takes a customer no more than 25 minutes to eat lunch.b. Economists have stated that the marginal propensity to consume is at least 90 out of every dollar.c. It has been stated that 75 out of every 100 people who go to the movies on Saturday night buy popcorn.

Q: Several years ago the proportion of Americans aged 18 " 24 who invested in the stock market was 0.20. A random sample of 25 Americans in this age group was recently taken. They were asked whether or not they invested in the stock market. The results follow:yesnonoyesnonoyesnonoyesnonononononononoyesnononoyesnonoAt a .05 level of significance, use Excel to determine whether or not the proportion of Americans 18 " 24 years old that invest in the stock market has changed.

Q: A manufacturer claims that at least 40% of its customers use coupons. A study of 25 customers is undertaken to test that claim. The results of the study follow.yesnonoyesyesnoyesnonoyesnonononoyesnonononoyesnonoyesnoyesAt a .05 level of significance, use Excel to test the manufacturer's claim.

Q: An official of a large national union claims that the fraction of women in the union is not significantly different from one-half. Using the sample information reported below, carry out a test of this statement. Use a .05 level of significance.sample size400women168men232

Q: A national poll reported that 58% of those with internet access have made purchases online. To investigate whether this percentage applies to its own state, a legislator commissions a study. A random sample of 400 state residents who have internet access is taken. Of those 400 respondents, 215 said that they have made purchases online. Does this sample provide sufficient evidence to conclude that the state differs from the nation with respect to making purchases online? Use the p-value to conduct the hypothesis test and use a .05 level of significance.

Q: For each shipment of parts a manufacturer wants to accept only those shipments with at most 10% defective parts. A large shipment has just arrived. A quality control manager randomly selects 50 of the parts from the shipment and finds that 6 parts are defective. Is this sufficient evidence to reject the entire shipment? Use a .05 level of significance to conduct the appropriate hypothesis test.

Q: A student believes that no more than 20% (i.e., ï‚£ 20%) of the students who finish a statistics course get an A. A random sample of 100 students was taken. Twenty-four percent of the students in the sample received A's.a. State the null and alternative hypotheses.b. Using a critical value, test the hypothesis at the 1% level of significance.c. Using a p-value, test the hypothesis at the 1% level of significance.

Q: A new soft drink is being market tested. A sample of 400 individuals participated in the taste test and 80 indicated they like the taste.a. At a 5% significance level, test to determine if at least 22% of the population will like the new soft drink.b. Determine the p-value.

Q: Consider the following hypothesis test:Ho: p= 0.5Ha: p0.5A sample of 800 provided a sample proportion of 0.58.a. Using = 0.05, what is the rejection rule?b. Determine the standard error of the proportion.c. Compute the value of the test statistic z. What is your conclusion?d. Determine the p-value.

Q: Consider the following hypothesis test:

Q: A manufacturer is considering a new production method. The current method produces 94% non-defective (good) parts. The new method will be implemented if it produces more non-defectives than the current method. Identify the hypotheses.

Q: In a television commercial, the manufacturer of a toothpaste claims that at least 4 out of 5 dentists recommend its product. A consumer-protection group wants to test that claim. Identify the hypotheses.

Q: A group of young businesswomen wish to open a high fashion boutique in a vacant store, but only if the average income of households in the area is more than $45,000. A random sample of 9 households showed the following results.$48,000$44,000$46,000$43,000$47,000$46,000$44,000$42,000$45,000Use the statistical techniques in Excel to advise the group on whether or not they should locate the boutique in this store. Use a .05 level of significance. (Assume the population is normally distributed.)

Q: You are given the following information obtained from a random sample of 4 observations.25473256At a .05 level of significance, use Excel to determine whether or not the mean of the population from which this sample was taken is significantly different from 48. (Assume the population is normally distributed.)

Q: You are given the following information obtained from a random sample of 5 observations.2018172218At a 10% level of significance, use Excel to determine whether or not the mean of the population from which this sample was taken is significantly less than 21. (Assume the population is normally distributed.)

Q: Nancy believes that the average running time of movies is equal to 140 minutes. A sample of 4 movies was taken and the following running times were obtained. Assume the distribution of the population is normally distributed.150150180170a. State the null and alternative hypotheses.b. Using a critical value, test the hypothesis at the 10% level of significance.c. Using a p-value, test the hypothesis at the 10% level of significance.d. Using a confidence interval, test the hypothesis at the 10% level of significance.e. Could a Type II error have been committed in this hypothesis test?

Q: A sample of 16 cookies is taken to test the claim that each cookie contains at least 9 chocolate chips. The average number of chocolate chips per cookie in the sample was 7.875 with a standard deviation of 1. Assume the distribution of the population is normal.a. State the null and alternative hypotheses.b. Using a critical value, test the hypothesis at the 1% level of significance.c. Using a p-value, test the hypothesis at the 1% level of significance.d. Compute the probability of a Type II error if the true number of chocolate chips per cookie is 8.

Q: A soft drink filling machine, when in perfect adjustment, fills the bottles with 12 ounces of soft drink. A random sample of 25 bottles is selected, and the contents are measured. The sample yielded a mean content of 11.88 ounces, with a standard deviation of 0.24 ounces. With a 0.05 level of significance, test to see if the machine is in perfect adjustment. Assume the distribution of the population is normal.

Q: In the past the average age of employees of a large corporation has been 40 years. Recently, the company has been hiring older individuals. In order to determine whether there has been an increase in the average age of all the employees, a sample of 25 employees was selected. The average age in the sample was 45 years with a standard deviation of 5 years. Assume the distribution of the population is normal. Let = .05.a. State the null and the alternative hypotheses.b. Test to determine whether or not the mean age of all employees is significantly more than 40 years.

Q: From a population of cans of coffee marked "12 ounces," a sample of 25 cans is selected and the contents of each can are weighed. The sample revealed a mean of 11.8 ounces and a standard deviation of 0.5 ounces. Test to see if the mean of the population is at least 12 ounces. (Assume the population is normally distributed.) Use a .05 level of significance.

Q: A carpet company advertises that it will deliver your carpet within 15 days of purchase. A sample of 49 past customers is taken. The average delivery time in the sample was 16.2 days. The population standard deviation is 5.6 days.a. State the null and alternative hypotheses.b. Using a critical value, test the null hypothesis at the 5% level of significance.c. Using a p-value, test the hypothesis at the 5% level of significance.d. Compute the probability of a Type II error if the true average delivery time is 17 days after purchase.

Q: A student believes that the average grade on the statistics final examination is 87. A sample of 36 final examinations is taken. The average grade in the sample is 83.96. The population variance is 144.a. State the null and alternative hypotheses.b. Using a critical value, test the hypothesis at the 5% level of significance.c. Using a p-value, test the hypothesis at the 5% level of significance.d. Using a confidence interval, test the hypothesis at the 5% level of significance.e. Compute the probability of a Type II error if the average grade on the final is 85.

Q: A carpet company advertises that it will deliver your carpet within 15 days of purchase. A sample of 49 past customers is taken. The average delivery time in the sample was 16.2 days. Assume the population standard deviation is known to be 5.6 days.a. State the null and alternative hypotheses.b. Using a critical value, test the null hypothesis at the 5% level of significance.c. Using a p-value, test the hypothesis at the 5% level of significance.d. What type of error may have been committed for this hypothesis test?

Q: A carpet company advertises that it will deliver your carpet within 15 days of purchase. A sample of 49 past customers is taken. The average delivery time in the sample was 16.2 days. Assume the population standard deviation is known to be 5.6 days.a. State the null and alternative hypotheses.b. Using a critical value, test the null hypothesis at the 5% level of significance.c. Using a p-value, test the hypothesis at the 5% level of significance.d. What type of error may have been committed for this hypothesis test?ANSWERS:

Q: Bastien, Inc. has been manufacturing small automobiles that have averaged 50 miles per gallon of gasoline in highway driving. The company has developed a more efficient engine for its small cars and now advertises that its new small cars average more than 50 miles per gallon in highway driving. An independent testing service road-tested 36 of the automobiles. The sample showed an average of 51.5 miles per gallon. The population standard deviation is 6 miles per gallon.a. With a 0.05 level of significance, test to determine whether or not the manufacturer's advertising campaign is legitimate.b. What is the p-value associated with the sample results?

Q: A lathe is set to cut bars of steel into lengths of 6 centimeters. The lathe is considered to be in perfect adjustment if the average length of the bars it cuts is 6 centimeters. A sample of 121 bars is selected randomly and measured. It is determined that the average length of the bars in the sample is 6.08 centimeters. The population standard deviation is 0.44 centimeters. Determine whether or not the lathe is in perfect adjustment. Use a .05 level of significance.

Q: A sample of 81 account balances of a credit company showed an average balance of $1,200. The population standard deviation is $126. You want to determine if the mean of all account balances is significantly different from $1,150. Use a .05 level of significance.

Q: In order to determine the average price of hotel rooms in Atlanta, a sample of 64 hotels was selected. It was determined that the average price of the rooms in the sample was $112. The population standard deviation is known to be $16. Use a 0.05 level of significance and determine whether or not the average room price is significantly different from $108.50.

Q: "D" size batteries produced by MNM Corporation have had a life expectancy of 87 hours. Because of an improved production process, the company believes that there has been an increase in the life expectancy of its "D" size batteries. A sample of 36 batteries showed an average life of 88.5 hours. Assume from past information that it is known that the standard deviation of the population is 9 hours.a. Use a 0.01 level of significance, and test to determine if there has been an increase in the life expectancy of the "D" size batteries.b. What is the p-value associated with the sample results? What is your conclusion, based on the p-value?

Q: Given below are seven observations collected in a regression study on two variables, x (independent variable) and y (dependent variable). Use Excel's Regression Tool to construct a residual plot and use it to determine if any model assumption have been violated.xy212396877867592

Q: A company has recorded data on the weekly sales for its product (y) and the unit price of the competitor's product (x). The data resulting from a random sample of 7 weeks follows. Use Excel's Regression Tool to construct a residual plot and use it to determine if any model assumption have been violated.WeekPriceSales1.33202.25143.44224.40215.35166.39197.2915

Q: Given below are seven observations collected in a regression study on two variables, x (independent variable) and y (dependent variable). Use Excel's Regression Tool to construct a residual plot and use it to determine if any model assumption have been violated.xy212396877867592

Q: A company has recorded data on the weekly sales for its product (y) and the unit price of the competitor's product (x). The data resulting from a random sample of 7 weeks follows. Use Excel to:a.compute a 95% confidence interval for expected sales for all weeks when the competitor's price is .30.b.compute a 95% prediction interval for sales for a week when the competitor's price is .30.WeekPriceSales1.33202.25143.44224.40215.35166.39197.2915

Q: Given below are seven observations collected in a regression study on two variables, x (independent variable) and y (dependent variable). Use Excel toa. compute a 95% confidence interval for E(y) when x= 5b. compute a 95% prediction interval for ywhen x= 5.xy212396877867592

Q: A company has recorded data on the weekly sales for its product (y) and the unit price of the competitor's product (x). The data resulting from a random sample of 7 weeks follows. Use Excel's Regression Tool to answer the following questions.WeekPriceSales1.33202.25143.44224.40215.35166.39197.2915a. What is the estimated regression equation?b. Perform a t test and determine whether or not xand yare related. Use = 0.05.c. Perform an F test and determine whether or not xand yare related. Use = 0.05.d. Find and interpret the coefficient of determination.PriceSales0.33200.25140.44220.4210.35160.39190.2915SUMMARY OUTPUTRegression StatisticsMultiple R0.877760967R Square0.770464315Adjusted R Sq.0.724557178Standard Error1.643764862Observations7ANOVAdfSSMSFSignific. FRegression145.3473345.3473316.783110.009385Residual513.509812.701963Total658.85714CoefficientsStandard Errort StatP-valueLower 95%Intercept3.5817884413.6082150.9926760.366447-5.69341Price41.6030534410.155214.0967190.00938515.49829

Q: Given below are seven observations collected in a regression study on two variables, x (independent variable) and y (dependent variable). Use Excel's Regression Tool to answer the following questions.xy212396877867592a. What is the estimated regression equation?b. Perform a ttest and determine whether or not xand yare related. Use = 0.05.c. Perform an Ftest and determine whether or not xand yare related. Use = 0.05.d. Find and interpret the coefficient of determination.xy212396877867592SUMMARY OUTPUTRegression StatisticsMultiple R0.9185587R Square0.84375Adjusted R Sq.0.8125Standard Error1.3693064Observations7ANOVAdfSSMSFSignificance FRegression150.62550.625270.00348Residual59.3751.875Total660CoefficientsStandard Errort StatP-valueLower 95%Intercept13.751.3983419.8330820.000185310.1555x-1.1250.216506-5.196150.0034782-1.68155

Q: Shown below is a portion of a computer output for regression analysis relating y (dependent variable) and x (independent variable).ANOVAdfSSRegression1882Residual204000Total214882CoefficientsStandard Errort StatIntercept5.003.56Variable x6.303.00a. What has been the sample size for the above?b. Perform a t-test and determine whether or not xand yare related. Use = 0.05.c. Perform an F-test and determine whether or not xand yare related. Use = 0.05.d. Compute the coefficient of determination.e. Interpret the meaning of the value of the coefficient of determination that you found in d. Be very specific.

Q: Given below are seven observations collected in a regression study on two variables, x (independent variable) and y (dependent variable). Use Excel to develop a scatter diagram and to compute the least squares estimated regression equation and the coefficient of determination.xy212396877867592Shown below is a portion of a computer output for a regression analysis relating y (dependent variable) and x (independent variable).ANOVAdfSSRegression150.58Residual1355.42Total14106.00CoefficientsStandard Errort StatIntercept16.1561.42Variable x-0.9030.26a. Perform a t test and determine whether or not yand xare related. Use = 0.05.b. Compute the coefficient of determination and fully interpret the meaning. Be very specific.

Q: A company has recorded data on the weekly sales for its product (y) and the unit price of the competitor's product (x). The data resulting from a random sample of 7 weeks follows. Use Excel to develop a scatter diagram and to compute the least squares estimated regression equation and the coefficient of determination.WeekPriceSales1.33202.25143.44224.40215.35166.39197.2915We are interested in determining the relationship between daily supply (y) and the unit price (x) for a particular item. A sample of ten days supply and associated price resulted in the following data.x = 66x2= 526y = 71y2= 605xy = 557a. Develop the least square estimated regression equation.b. Compute the coefficient of determination and fully explain its meaning.c. At = 0.05, perform a t-test and determine if the slope is significantly different from zero.

Q: A company has recorded data on the daily demand for its product (y in thousands of units) and the unit price (x in hundreds of dollars). A sample of 15 days demand and associated prices resulted in the following data. x = 75 x 2 = 437 y = 180 y 2 = 2266 x y = 844a. Using the above information, develop the least-squares estimated regression line and write the equation.b. Compute the coefficient of determination.c. Perform an Ftest and determine whether or not there is a significant relationship between demand and unit price. Let = 0.05.d. Would the demand ever reach zero? If yes, at what price would the demand be zero?

Q: A company has recorded data on the daily demand for its product (y in thousands of units) and the unit price (x in hundreds of dollars). A sample of 15 days demand and associated prices resulted in the following data. x = 75 x 2 = 437 y = 180 y 2 = 2266 x y = 844a. Using the above information, develop the least-squares estimated regression line and write the equation.b. Compute the coefficient of determination.c. Perform an Ftest and determine whether or not there is a significant relationship between demand and unit price. Let= 0.05.d. Would the demand ever reach zero? If yes, at what price would the demand be zero?

Q: A company has recorded data on the daily demand for its product (y in thousands of units) and the unit price (x in hundreds of dollars). A sample of 15 days demand and associated prices resulted in the following data. x = 75x 2 = 469 y = 135 y 2 = 1315 x y = 616a. Using the above information, develop the least-squares estimated regression line and write the equation.b. Compute the coefficient of determination.c. Perform an Ftest and determine whether or not there is a significant relationship between demand and unit price. Let = 0.05.d. Would the demand ever reach zero? If yes, at what price would the demand be zero?

Q: Given below are seven observations collected in a regression study on two variables, x (independent variable) and y (dependent variable). Use Excel to develop a scatter diagram and to compute the least squares estimated regression equation.xy212396877867592A company has recorded data on the daily demand for its product (y in thousands of units) and the unit price (x in hundreds of dollars). A sample of 11 days demand and associated price resulted in the following data. x = 154 x 2 = 2,586 y =451 y 2 = 18,901 x y = 5,930a. Using the above information, develop the least-squares estimated regression line.b. Compute the coefficient of determination.c. Perform an Ftest and determine whether or not there is a significant relationship between demand and unit price. Let = 0.05.d. Perform a t test to determine whether the slope is significantly different from zero. Let = 0.05.e. Would the demand ever reach zero? If yes, at what price would the demand be zero. Show your complete work.

Q: Given below are seven observations collected in a regression study on two variables, x (independent variable) and y (dependent variable).xy212396877867592a. Develop the least squares estimated regression equation.b. At 95% confidence, perform a ttest and determine whether or not the slope is significantly different from zero.c. Perform an Ftest to determine whether or not the model is significant. Let = 0.05.d. Compute the coefficient of determination.

Q: At a local university, a sample of 49 evening students was selected in order to determine whether the average age of the evening students is significantly different from 21. The average age of the students in the sample was 23 years. The population standard deviation is known to be 3.5 years. Determine whether or not the average age of the evening students is significantly different from 21. Use a 0.1 level of significance.

Q: At a local university, a sample of 49 evening students was selected in order to determine whether the average age of the evening students is significantly different from 21. The average age of the students in the sample was 23 years. The population standard deviation is known to be 3.5 years. Determine whether or not the average age of the evening students is significantly different from 21. Use a 0.1 level of significance.H0: = 21Ha: 21 z= 4; therefore, reject H0, there is sufficient evidence at = .1 to conclude that the average age of the evening students is significantly different from 21

Q: The average gasoline price of one of the major oil companies has been $1.00 per gallon. Because of shortages in production of crude oil, it is believed that there has been a significant increase in the average price. In order to test this belief, we randomly selected a sample of 36 of the company's gas stations and determined that the average price for the stations in the sample was $1.10. Assume that the standard deviation of the population () is $0.12.a. State the null and the alternative hypotheses.b. Test the claim at = .05.c. What is the p-value associated with the above sample results?

Q: A fast food restaurant is considering a promotion that will offer customers to purchase a toy featuring a cartoon movie character. If more than 20% of the customers purchase the toy, the promotion will be profitable. A sample of 50 restaurants is used to test the promotion.a. State the hypotheses associated with the restaurant's test.b. Describe a Type I error for this situation.c. Describe a Type II error for this situation.

Q: At a certain manufacturing plant, a machine produced ball bearings that should have a diameter of 0.50 mm. If the machine produces ball bearings that are either too small or too large, the ball bearings must be scrapped. Every hour, a quality control manager takes a random sample of 30 ball bearings to test to see if the process is "out of control" (i.e. to test to see if the average diameter differs from 0.50 mm).a. State the hypotheses associated with the manager's test.b. Describe a Type I error for this situation.c. Describe a Type II error for this situation.

Q: A researcher is testing a new painkiller that claims to relieve pain in less than 15 minutes, on average.a. State the hypotheses associated with the researcher's test.b. Describe a Type I error for this situation.c. Describe a Type II error for this situation.

Q: The manager of a department store wants to determine what proportion of people who enter the store use the store's credit card for their purchases. What size sample should he take so that at 99% confidence the error will not be more than 8%?

Q: A local hotel wants to estimate the proportion of its guests that are from out-of-state. Preliminary estimates are that 45% of the hotel guests are from out-of-state. How large a sample should be taken to estimate the proportion of out-of-state guests with a margin of error no larger than 5% and with a 95% level of confidence?

Q: A health club annually surveys its members. Last year, 33% of the members said they use the treadmill at least 4 times a week. How large of sample should be taken this year to estimate the percentage of members who use the treadmill at least 4 times a week? The estimate is desired to have a margin of error of 5% with a 95% level of confidence.

Q: A survey of 40 students at a local college asks, "Where do you buy the majority of your books?" The responses fell into three categories: "at the campus bookstore," "on the Internet," and "other." The results follow. Use Excel to estimate the proportion of all of the college students who buy their books on the Internet.Where Most Books Boughtbookstorebookstoreinternetotherinternetotherbookstoreotherbookstorebookstorebookstorebookstorebookstoreotherbookstorebookstorebookstoreinternetinternetotherotherotherotherotherotherotherinternetbookstoreotherotherinternetotherbookstorebookstoreotherbookstoreinternetinternetotherbookstore

Q: A new brand of breakfast cereal is being market tested. One hundred boxes of the cereal were given to consumers to try. The consumers were asked whether they liked or disliked the cereal. You are given their responses below.ResponseFrequencyLiked60Disliked40100a. What is the point estimate of the proportion of people who will like the cereal?b. Construct a 95% confidence interval for the proportion of all consumers who will like the cereal.c. What is the margin of error for the 95% confidence interval that you constructed in part b?d. With a .95 probability, how large of a sample needs to be taken to provide a margin of error of .09 or less?

Q: A university planner wants to determine the proportion of spring semester students who will attend summer school. She surveys 32 current students discovering that 12 will return for summer school.a. Construct a 90% confidence interval estimate for the proportion of current spring students who will return for summer school.b. With a 0.95 probability, how large of a sample would have to be taken to provide a margin of error of 3% or less?

Q: In a random sample of 200 registered voters, 120 indicated they are Democrats. Develop a 95% confidence interval for the proportion of registered voters in the population who are Democrats.

Q: It is known that the variance of a population equals 484. A random sample of 81 observations is going to be taken from the population.a. With a .80 probability, what statement can be made about the size of the margin of error?b. With a .80 probability, how large of a sample would have to be taken to provide a margin of error of 3 or less?

Q: For inventory purposes, a grocery store manager wants to estimate the mean number of pounds of cat food sold per month. The estimate is desired to be within 10 pounds with a 95% level of confidence. A pilot study provided a standard deviation of 27.6 pounds. How many months should be sampled?

Q: A real estate agent wants to estimate the mean selling price of two-bedroom homes in a particular area. She wants to estimate the mean selling price to within $10,000 with an 89.9% level of confidence. The standard deviation of selling prices is unknown but the agent estimates that the highest selling price is $1,000,000 and the lowest is $50,000. How many homes should be sampled?

Q: If the standard deviation for the lifetimes of washing machines is estimated to be 800 hours, how large a sample must be taken in order to be 97% confident that the margin of error will not exceed 50 hours?

Q: A researcher is interested in determining the average number of years employees of a company stay with the company. If past information shows a standard deviation of 7 months, what size sample should be taken so that at 95% confidence the margin of error will be 2 months or less?

Q: If the standard deviation of the lifetimes of vacuum cleaners is estimated to be 300 hours, how large of a sample must be taken in order to be 97% confident that the margin of error will not exceed 40 hours?

Q: A coal company wants to determine a 95% confidence interval estimate for the average daily tonnage of coal that they mine. Assuming that the company reports that the standard deviation of daily output is 200 tons, how many days should they sample so that the margin of error will be 39.2 tons or less?

Q: The monthly starting salaries of students who receive an MBA degree have a standard deviation of $110. What size sample should be selected to obtain a 0.95 probability of estimating the mean monthly income within $20 or less?

Q: Below you are given ages that were obtained by taking a random sample of 9 undergraduate students.192223192122192321Use Excel to determine an interval estimate for the mean of the population at a 99% confidence level. Interpret your results.

Q: A local university administers a comprehensive examination to the recipients of a B.S. degree in Business Administration. A sample of 5 examinations is selected at random and scored. The scores are shown below.Grade5685658693Use Excel to determine an interval estimate for the mean of the population at a 98% confidence level. Interpret your results.

Q: Fifty students are enrolled in an Economics class. After the first examination, a random sample of 5 papers was selected. The grades were 60, 75, 80, 70, and 90.a. Calculate the estimate of the standard error of the mean.b. What assumption must be made before we can determine an interval for the mean grade of all the students in the class? Explain why.c. Assume the assumption of Part b is met. Provide a 90% confidence interval for the mean grade of all the students in the class.d. If there were 200 students in the class, what would be the 90% confidence interval for the mean grade of all the students in the class?

Q: The monthly incomes from a random sample of faculty at a university are shown below. Monthly Income ($1000s)3.04.06.03.05.05.06.08.0 Compute a 90% confidence interval for the mean of the population. The population of all faculty incomes is known to be normally distributed. Give your answer in dollars.

Q: The monthly incomes from a random sample of faculty at a university are shown below.

Q: You are given the following information obtained from a random sample of 4 observations from a large, normally distributed population.25473256a. What is the point estimate of ?b. Construct a 95% confidence interval for .c. Construct a 90% confidence interval for .d. Discuss why the 90% and 95% confidence intervals are different.

Q: A random sample of 25 observations was taken from a normally distributed population. The average in the sample was 84.6 with a variance of 400.a. Construct a 90% confidence interval for .b. Construct a 99% confidence interval for .c. Discuss why the 90% and 99% confidence intervals are different.d. What would you expect to happen to the confidence interval in part a if the sample size was increased? Be sure to explain your answer.

Q: The makers of a soft drink want to identify the average age of its consumers. A sample of 16 consumers is taken. The average age in the sample was 22.5 years with a standard deviation of 5 years. Assume the population of consumer ages is normally distributed.a. Construct a 95% confidence interval for the average age of all the consumers.b. Construct an 80% confidence interval for the average age of all the consumers.c. Discuss why the 95% and 80% confidence intervals are different.

Q: A random sample of 36 magazine subscribers is taken to estimate the mean age of all subscribers. The data follow. Use Excel to construct a 90% confidence interval estimate of the mean age of all of this magazine's subscribers.SubscriberAgeSubscriberAgeSubscriberAge139134025382271435265133815352726433164128395401734293563518463037751194431338362044324194721433336102822323433113323293546123524333637

Q: In order to determine how many hours per week freshmen college students watch television, a random sample of 256 students was selected. It was determined that the students in the sample spent an average of 14 hours. The standard deviation is 3.2 hours per week for all freshman college students.a. Provide a 95% confidence interval estimate for the average number of hours that all college freshmen spend watching TV per week.b. Suppose the sample mean came from a sample of 25 students. Provide a 95% confidence interval estimate for the average number of hours that all college freshmen spend watching TV per week. Assume that the hours are normally distributed.

Q: A sample of 100 cans of coffee showed an average weight of 13 ounces. The population standard deviation is 0.8 ounces.a. Construct a 95% confidence interval for the mean of the population.b. Construct a 95.44% confidence interval for the mean of the population.c. Discuss why the answers in parts a and b are different.

Q: The average monthly electric bill of a random sample of 256 residents of a city is $90. The population standard deviation is assumed to be $24.a. Construct a 90% confidence interval for the mean monthly electric bills of all residents.b. Construct a 95% confidence interval for the mean monthly electric bills of all residents.