I need help in working this, please.

Suppose you are the manager of Speedy Oil Change which claims that it will change the oil in

customers' cars in less than 30 minutes on average. Further suppose that several complaints have

been filed from customers stating that their oil change took longer than 30 minutes. Upper-level

management at Speedy Oil Change headquarters has requested that you investigate the complaints.

To begin your investigation, you randomly audit 36 oil changes performed by Speedy Oil Change and

record the time each customer waited for the oil change. The number of minutes to complete each of

the 36 oil changes is reported below.

42 29 19 11 10 27

41 27 22 26 28 32

17 15 25 35 32 22

13 31 17 30 33 25

18 24 28 21 40 19

34 30 14 23 22 10

(data similar to http://org.elon.edu/econ/sac/Descriptive.htm)

In the questions below, you will test if the mean is significantly less than 30 minutes at a significance

level of 0.01.

1. List the three requirements that should be met for this hypothesis test. Have the requirements

been met?

2. Write the null and alternative hypothesis.

3. Calculate the test statistic and the P-value. Label each accordingly.

4. Would you reject the null hypothesis? Justify your answer using a complete sentence and proper

grammar.

5. Is the company fulfilling its promise to "change the oil in customers' cars in less than 30 minutes on

average?"

Unfortunately, Speedy Oil Change continues to get customer complaints. As the manager, you feel

that perhaps more analysis is needed. You know that you are likely to be asked "how much less than

30 minutes is our mean oil change?"

6. Construct a 98% confidence interval. Report this confidence interval accurate to 1 decimal place.

7. Using the confidence interval above, calculate and label the point estimate and the margin of error

below.

8. Explain to your superiors how to interpret this interval.

9. Using the confidence interval you created, calculate the range of values that answers the question

"how much less than 30 minutes is our mean oil change?"

10. What other real-world factors might you need to consider in order to address the customer

complaints? (i.e. what else could cause a longer wait time?)