Question: Fast ‘n Clean operates 12 laundromats on the east side of the city. All of Fast ‘n Clean’s clothes dryers have a label stating “20 minutes for $1.00.” You question the accuracy of the dryers’ clocks and decide to conduct an observational study. You randomly select 36 dryers in several different Fast ‘n Clean locations, put $1.00 in each and time the drying cycle. The sample mean drying time is 20 minutes and 25 seconds. The manufacturer of the dryer states that the standard deviation for 20-minute drying cycles is 1 minute.

Use a sample size of n = 36 for this two-tailed test. Test at a level of significance of 5%.

A) State the null and alternative hypotheses.

B) What is the test statistic?

C) What is the p-value? Should the null hypothesis be rejected or not be rejected using the p-value approach? Explain your answer.

D) What are the critical values? Should the null hypothesis be rejected or not be rejected using the critical value approach? Explain your answer.

E) Setup a 95% confidence interval. Should the null hypothesis be rejected or not be rejected using the confidence interval approach? Explain your answer.