The manager of a branch of a major bank wants to improve service. She is thinking about giving $1 to any customer who waits in line for a period of time that is considered excessive. (The bank ultimately decided that more than 8 minutes is excessive). However, to get a better idea about the level of current service, she undertakes a survey of customers. A student is hired to measure the time spent waiting in line by a random sample of 50 customers. Using a stopwatch, the student determined the amount of time between the time the customer joined the line and the time he or she reached the teller. The times were recorded. Please use the data below. If possible, please explain how to solve this question in Excel.

a. Construct a 90% confidence Interval estimate of the mean waiting time for the bank's customers. Interpret your answer.

b. Perform a 1 sample t-test to test the claim that the mean wait time is less than 8 mins. Test at a significance level of 5%.

Times

1.4

6.1

10.4

6.4

3.5

9.0

10.9

4.8

9.0

5.6

9.6

9.4

5.6

6.6

1.2

3.9

1.4

6.6

8.9

7.1

4.8

5.2

3.2

2.4

5.8

3.9

5.9

10.7

4.1

6.8

2.9

2.0

7.2

8.6

5.9

7.5

4.5

1.9

1.0

3.9

8.7

3.2

4.6

4.0

4.1

2.3

11.0

10.8

7.3

7.9