Question

25. The​ quality-control manager at a compact fluorescent light bulb​ (CFL) factory needs to determine whether the mean life of a large shipment of CFLs is equal to 7,485 hours. The population standard deviation is 840 hours. A random sample of 49 light bulbs indicates a sample mean life of 7,305 hours

At the 0.05 level of​ significance, is there evidence that the mean life is different from 7485?

Determine the null​ hypothesis, and the alternative​ hypothesis

What is the test​ statistic?

What​ is/are the critical​ value(s)?

What is the final​ conclusion?

What is the​ p-value?

Interpret the meaning of the​ p-value.

Construct a​ 95% confidence interval estimate of the population mean life of the light bulbs.

Compare the results of​ (a) and​ (c). What conclusions do you​ reach?

28. You are the manager of a restaurant for a​ fast-food franchise. Last​ month, the mean waiting time at the​ drive-through window for branches in your geographical​ region, as measured from the time a customer places an order until the time the customer receives the​ order, was 3.7 minutes. You select a random sample of 81 orders. The sample mean waiting time is 3.89 minutes, with a sample standard deviation of 0.9 minutes.

At the 0.10 level of​ significance, is there evidence that the population mean waiting time is different from 3.7 minutes? State the null and alternative hypotheses.

Determine the test statistic

Find the​ p-value.

State the conclusion.

Because the sample size is 81​, do you need to be concerned about the shape of the population distribution when conducting the t test in​ (a)? Explain. Choose the correct answer below.

Answer 1