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Q:
25 A discrete variable is one that
a) is kept a secret.
b) we cannot estimate.
c) can take on a limited number of possible values.
d) can take on any value between -ï‚¥ and +ï‚¥.
Q:
24 Two events are said to be independent if
a) the occurrence of one precludes the occurrence of the other.
b) the occurrence of both is impossible.
c) both events happen simultaneously.
d) the occurrence of one has no effect on the probability of the occurrence of the other.
Q:
23+ I would like to calculate the probability that you will do well in this course if you are a member of a group of students who study together. The most important word in that last sentence is
a) "if."
b) "calculate."
c) "I."
d) "study."
Q:
22 The vertical bar "|" is read as _______ when we are talking about probabilities.
a) "absolute"
b) "not"
c) "divide"
d) "given"
Q:
21 When we are talking about joint probabilities we are likely to invoke
a) the multiplicative rule.
b) the additive rule.
c) the subjective probability rule.
d) the law of joint probabilities.
Q:
20 If I am interested in the probability that you will be depressed if you have experienced a great deal of stress in the past month, I am talking about
a) independence.
b) a joint probability.
c) a conditional probability.
d) an additive probability.
Q:
19+ If I am interested in the probability that you will be depressed and that you will have experienced a great deal of stress in the past month, I am talking about
a) independence.
b) a joint probability.
c) a conditional probability.
d) an additive probability.
Q:
18 One difference between the additive and the multiplicative rules that helps us remember when to use which is
a) with the additive rule we are talking about the occurrence of one of several outcomes.
b) with the multiplicative rule we are talking about the occurrence of more than one kind of outcome.
c) the two rules are interchangeable.
d) both a and b
Q:
17 Once again using the example about supermarket fliers, we would have evidence that the "don"t litter" message on the flier was effective if we found that
a) the probability of finding a flier with the message in the trash can was substantially higher than the probability calculated on the assumption that the two events were independent.
b) the probability of finding a flier with the message in the trash can was substantially lower than the probability calculated on the assumption that the two events were independent.
c) the probability of finding a flier with the message in the trash can was the same as the probability calculated on the assumption that the two events were independent.
d) We can"t tell from the information available.
Q:
16+ Using the example from the text about the supermarket fliers, when we calculate the probability that a flier will be left either among the canned goods or in the bottom of the shopping cart, we need to invoke
a) the additive rule.
b) the superlative rule.
c) the dependence rule.
d) the multiplicative rule.
Q:
15+ Using an example from the text, when we calculate the probability that a supermarket flier will be left among the canned goods if it contains a notice not to litter, we will be dealing with
a) the additive rule.
b) the superlative rule.
c) the dependence rule.
d) conditional probabilities.
Q:
14 When we want to calculate the probability of the joint occurrence of two or more independent events, we invoke
a) the multiplicative rule.
b) the additive rule.
c) the sum of independent probabilities.
d) Bernoulli's rule.
Q:
13 An exhaustive set of events is one which
a) we can never estimate.
b) contains all possible outcomes.
c) contains only independent events.
d) comes from running a very long series of sampling studies.
Q:
12+ Two events are mutually exclusive when
a) the occurrence of one event is independent of the occurrence of the other.
b) the occurrence of one event precludes the occurrence of the other.
c) both events are equally likely.
d) the first event precedes the second event.
Q:
11 To estimate that probability that the next vehicle to leave the parking lot will be a silver pickup, we first need to
a) assume that the color and the type of vehicle are mutually exclusive.
b) assume that the color and the type of vehicle are independent.
c) assume that the color and the type of vehicle are exhaustive.
d) simply multiply the two probabilities.
Q:
10 In the parking lot below me, 40% of the vehicles are silver, and about 25% of the vehicles are pickup trucks. The probability that the next vehicle to leave the parking lot will be a silver pickup is
a) .40
b) .65
c) .10
d) It can"t be estimated without knowing that color and type of vehicle are independent.
Q:
9+ I am looking down on a parking lot, and can see that about 10% of the cars are red and about 15% of the cars are blue. To estimate the probability that the next car to leave the lot will be red or blue, I would
a) add those two percentages.
b) multiply those two percentages.
c) count the number of green cars.
d) It can"t be estimated from the information provided.
Q:
8 Following up on the preceding question, suppose that you found that 27 of the new hires were women. You would probably be justified in concluding that
a) there was discrimination against men.
b) there was discrimination against women.
c) there was no discrimination on the basis of gender.
d) we don"t have enough information to even start to answer the question.
Q:
7 Last year there were 300 new Ph.D.s in chemistry looking for academic jobs. Of those, 100 were women and 200 were men. Nationwide last year there were 75 new hirings in chemistry departments. How many of those new hires would be expected to be women if there was no gender discrimination?
a) 15
b) 20
c) 25
d) 50
Q:
6+ Out of a pool of 40 men and 10 women, all of whom are equally qualified for one position as an instructor in chemistry, the person hired was a male. The probability that this would happen if the department ignored gender as a variable in selection is
a) .40
b) .80
c) .50
d) .63
Q:
5 Of 50 women treated for breast cancer in the local cancer unit, 35 of them survived for at least 5 years. For a woman who has just been diagnosed with breast cancer, our best guess is that the probability that she will survive for 5 years is
a) 35/50 = .70
b) 15/35= .43
c) 35/100 = .35
d) we don"t have enough information.
Q:
4 Which of the following is NOT a way of setting probabilities?
a) the analytic view
b) the frequentistic view
c) the subjective view
d) the correlational view
Q:
3+ A frequentistic approach to probability is likely to be invoked
a) in predicting the weather.
b) in calculating the chances of winning in craps.
c) in estimating the probability that a sharpshooter will score a bull's eye.
d) in blackjack.
Q:
2+ Where is "subjective probability" most likely to be invoked?
a) in setting the point spread in football
b) in deciding if tomorrow will be a good day
c) in calculating your best strategy in poker
d) in playing Russian roulette
Q:
1 Which of the following is NOT an appropriate use of probability?
a) estimating the likelihood that a particular event will occur
b) calculating your chances of winning the lottery
c) placing bets at the track
d) knowing what event will happen next
Q:
61 A professor rated how frequently students actively participated in class and then calculated the probability of getting various grades broken down by participation. The data follow: A B C D FFrequently .06 .20 .03 .01 .00Sometimes .03 .12 .20 .03 .02Rarely/Never .01 .08 .07 .06 .08a) What is the simple probability of getting an A?b) What is the probability of getting an A given the student participated frequently?c) What is the simple probability of failing?d) What is the probability of failing given the student participated rarely/never?
Q:
60 A local private school is selling raffle tickets for a new sports car. They plan to sell 10,000 tickets.
a) What is the probability that you will win if you bought 1 ticket?
b) How many tickets are needed to have a .25 probability of winning?
Q:
59 A kindergarten teacher assigns chores to her students on a weekly basis. One student works on each task, and each student is assigned only one task a week. During the first week of school, there were 20 students and 7 tasks. Also, 4 of the students had brown hair.
a) What is the probability that a student would not be assigned a chore?
b) What is the probability that a student had brown hair?
c) What is the probability that a student had brown hair or had a chore?
d) What is the probability that a student had brown hair and a chore?
Q:
58 If the average score on the Graduate Record Exam was 500 and the standard deviation was 100, what is the probability that a random student would score between 400 and 600?
Q:
57 A safety agency was interested in whether penalties for talking on a cell phone while driving reduce the probability that individuals will DO SO. They randomly contacted 100 cell phone users. Fifty were from a state that had a law prohibiting this behavior, and 50 were from a state that had no such law. The data follow: Use Cell Phone While Driving Do Not Use Cell Phone While Driving TotalLaw 10 40 50No Law 20 30 50Total 30 70 100a) Calculate the simple probability that someone uses a cell phone while driving.b) Calculate the joint probability that someone is in a state without the law and uses their cell phone while driving.c) Calculate the probability that someone will use their cell phone while driving given they live in state with the law.
Q:
56 Imagine the same bag of marbles, but this time, marbles are NOT returned to the bag after each draw.
a) What is the probability of drawing 3 clear marbles in 3 draws?
b) What is the probability of drawing a clear marble, then a green, and then a clear?
c) What is the probability of not selecting any clear marbles in three draws?
Q:
55 A bag of 100 marbles contains 30 blue marbles, 25 green marbles, 25 mixed green/blue marbles, and 20 clear marbles. Marbles are returned to the bag after every draw.
a) What is the probability of selecting a blue marble?
b) What is the probability of selecting a blue or green marble?
c) What is the probability of selecting a marble that is not clear?
d) What is the probability of selecting a blue marble on the first draw and then a clear marble on the second draw?
Q:
54 Your friend plays the lottery every day. Since he has never won, he is convinced that the odds that he will win next time are even better. From a probability perspective, what is wrong with your friend's logic?
Q:
53 Explain why it is important to know if someone is sampling with or without replacement when calculating the probability of multiple events.
Q:
52 Identify each of the following examples as the analytic, relative frequency, or subjective view of probability based on the example of a brother and sister playing scrabble:
a) If the brother and sister are equally matched, there is a .50 probability that each will win the game.
b) If the sister won 3 of the last 4 games, the probability that she will win this one is .75.
c) The brother believes there is an 80% chance that he will beat his sister this time.
Q:
51 The probability that an event will occur ranges from "1 to 1.
Q:
50 The probability that a student is a Psychology major given that she is female is an example of joint probability.
Q:
49 If the probability is .90 that a student taking this class is a Psychology major, and the probability that a student in this class has red hair is .05, then the joint probability of being a Psychology major and a red head in this class is .95.
Q:
48 I have a hunch that tomorrow is going to be a bad day. This is an example of the subjective probability.
Q:
47 Predicting the political party of the next president based on previous election patterns is an example of the relative frequency view of probability.
Q:
46 Dealing 5 cards from a standard deck is an example of sampling with replacement.
Q:
45 When observing a continuous variable, you can calculate the probability that an event falls in a certain interval; and when observing a discrete variable, you can calculate the probability of a specific outcome.
Q:
44 The probability of getting heads twice when flipping a coin 2 times is .50.
Q:
43 A bag of 100 hard candies included 30 butterscotch, 40 peppermint, 15 strawberry, 10 orange, and 5 banana. The probability that the first candy pulled out of the bag will be butterscotch or strawberry is .45.
Q:
42 The probability of rolling a 6 on the first roll with a standard die is independent of the probability of rolling a 6 on the second roll.
Q:
41 Two events are mutually exclusive if
a) they cannot both happen at the same time.
b) they cover all possibilities.
c) one of them must happen.
d) none of the above
Q:
59 In a normal distribution, indicate what percent of scores fall:
a) between the mean and 1 standard deviation above the mean
b) between plus and minus 2 standard deviations of the mean.
c) 3 standard deviations above or below the mean.
Q:
58 At a neighboring university, the average salary is also $45,000 and the distribution is normal. If $47,000 has a z score of 1.5, what is the standard deviation?
Q:
57 If the salary of assistant professors in this university is normally distributed with a mean of $45,000 and a standard deviation of $1,500, what salary would have a z score of .97?
Q:
56 The basketball team lives in another dorm from those in the previous question. Their heights are normally distributed as well, with a mean height of 71 inches and a standard deviation of 2 inches.
a) Draw their distribution on the same graph as students who lived in the first dorm (e.g., draw separate but overlapping distributions).
b) What percent of students in the first dorm are at least as tall as the average basketball players?
c) What percent of basketball players are taller than the average dorm resident?
Q:
55 Based on the previous data, we could conclude that 90% of the students are likely to fall between what heights?
Q:
54 Based on the height data in the previous question:
a) What percent of residents are between 65 inches and 71 inches tall?
b) What percent of residents are taller than 72 inches?
c) What percent of residents are shorter than 72 inches?
Q:
53 The height of students in a dormitory is normally distributed with a mean of 68 inches and a standard deviation of 3 inches. Draw the distribution.
Q:
52 Using the distribution in the previous question, calculate z scores for:
a) X = 11
b) X = 35
c) X = 71
Q:
51 Create a z distribution based on the following data. Explain the process.
10 20 20 30 30 30 40 40 40 40 50 50 50 60 60 70
Q:
50 The birth weight of healthy, full term infants in the United States is nearly normally distributed. The mean weight is 3,500 grams, and the standard deviation is 500 grams.
a) What percent of healthy newborns will weigh more than 3,250 grams?
b) What weights would 95% of all healthy newborns tend to fall between?
c) What is the z score for an infant who weighs 2,750 grams?
Q:
49 In a normal distribution, the majority of scores fall beyond plus or minus one standard deviation from the mean.
Q:
48 The probability that a student will score between plus or minus one standard deviation from the mean on an exam, assuming the scores are normally distributed, is approximately 68%.
Q:
47 Suzie scored in the 95th percentile on the Math portion of the SAT. This means that she scored as high or higher than 95% of the other students who took the test.
Q:
46 Performing a linear transformation can make any distribution normal.
Q:
45 A z score refers to the number of standard deviations above or below the mode.
Q:
44 The area under a particular portion of the normal curve is equivalent to theprobability of falling within that portion of the distribution.
Q:
43 The standard normal distribution is a normal distribution with a mean of 0 and a standard deviation of 1.
Q:
42 Most statistical techniques are based on the assumption that the population of observations is not normal.
Q:
41 The normal distribution is bimodal and symmetric.
Q:
40 The normal distribution is often referred to as the bell curve.
Q:
39 In a normal distribution, about how much of the distribution lies within two (2) standard deviations of the mean?
a) 33% of the distribution
b) 50% of the distribution
c) 66% of the distribution
d) 95% of the distribution
Q:
38 A normal distribution
a) has more than half of its data points to the left of the median.
b) has more than half of its data points to the right of the mean.
c) has 95% of its data points within one standard deviation of the mean.
d) is symmetrical.
Q:
37 For a normal distribution
a) all of the data points lie within one standard deviation from the mean.
b) about 2/3 of the distribution lies within one standard deviation from the mean.
c) about 95% of the distribution lies within two standard deviations from the mean.
d) both b and c
Q:
36 The most common situation in statistical procedures is to assume that
a) data are positively skewed.
b) data are negatively skewed.
c) data are normally distributed.
d) it doesn't make any difference what the distribution of the data looks like.
Q:
35 An example of a linear transformation is
a) converting heights from feet to meters.
b) subtracting the value of the mean from each individual IQ score and dividing by the value of the standard deviation.
c) both a and b
d) none of the above
Q:
34 The difference between a normal distribution and a standard normal distribution is
a) standard normal distributions are more symmetric.
b) normal distributions are based on fewer scores.
c) standard normal distributions always have a mean of 0 and a standard deviation of 1.
d) there is no difference.
Q:
33 The advantage of using T-scores and standard scores isa) those scores provide a common form of reference to everyone using them.b) only negative numbers are used.c) the mean is always 10.d) scores of -1 and +1 are equal distances from the mean.
Q:
32 "Abscissa" is to _______ as "ordinate" is to _______.
a) density; frequency
b) frequency; density
c) horizontal; vertical
d) vertical; horizontal
Q:
31+ A test score of 84 was transformed into a standard score of -1.5. If the standard deviation of test scores was 4, what is the mean of the test scores?a) 78b) 80c) 90d) 88
Q:
30+ If the test scores on an art history exam were normally distributed with a mean of 76 and standard deviation of 6, we would expect
a) most students scored around 70.
b) no one scored 100 on the exam.
c) almost equal numbers of students scored a 70 and an 82.
d) both a and c
Q:
29+ The difference between a standard score of -1.0 and a standard score of 1.0 isa) the standard score 1.0 is farther from the mean than -1.0.b) the standard score -1.0 is farther from the mean than 1.0.c) the standard score 1.0 is above the mean while -1.0 is below the mean.d) the standard score -1.0 is above the mean while 1.0 is below the mean.
Q:
28 Which of the following is NOT always true of a normal distribution?
a) It is symmetric.
b) It has a mean of 0.
c) It is unimodal.
d) both a and b
Q:
27 Transforming a set of data to a new mean and standard deviation using a linear transformation
a) alters the shape of the distribution.
b) makes the scores harder to work with.
c) is rarely permissible.
d) is something we do frequently.
Q:
26 Stanine scores
a) are badly skewed.
b) have a mean of 5 and vary between 1 and 9.
c) are always integers.
d) both b and c