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Question
NARRBEGIN: SA_66_69Suppose a firm that produces light bulbs wants to know whether it can say that its light bulbs typically last more than 1500 hours. Hoping to find support for their claim, the firm collects a random sample and records the lifetime (in hours) of each bulb. The information related to the hypothesis test is presented below.
Test of
1500 versus one-tailed alternative| Hypothesized mean | 1500 |
| Sample mean | 1509.5 |
| Std error of mean | 4.854 |
| Degrees of freedom | 24 |
| t-test statistic | 1.953 |
| p-value | 0.031 |
(A) Can the sample size be determined from the information above? Yes or no? If yes, what is the sample size in this case?
(B) The firm believes that the mean life is actually greater than 1500 hours, should you conduct a one-tailed or a two-tailed hypothesis test? Explain your answer, and state the appropriate null and alternative hypotheses.
(C) What is the sample mean of this data? If you use a 5% significance level, would you conclude that the mean life of the light bulbs is typically more than 1500 hours? Explain your answer.
(D) If you were to use a 1% significance level in this case, would you conclude that the mean life of the light bulbs is typically more than 1500 hours? Explain your answer.
Answer
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