1. A bank officer wants to determine the amount of the average total monthly deposits per customer at the bank. He believes an estimate of this average amount using a confidence interval is sufficient. He assumes the standard deviation of total monthly deposits for all customers is about $850.7. How large a sample should he take to be within $240 of the actual average with 90% confidence?

2. The manager of a local restaurant would like to estimate the average amount of time spent by its customers waiting to be assigned a table during peak hours (usually weekends and holidays). A random sample of 15 customers who visited the restaurant during peak hours was selected and the amount of time they spent waiting for a table is recorded. What is the point estimate of the mean () amount of time spent by customers waiting for a table during peak hours ?

Customers	Time spent (minutes)
1	42.12
2	35.62
3	98.46
4	63.14
5	76.28
6	86.88
7	30.38
8	51.11
9	31.43
10	52.94
11	52.19
12	51.11
13	33.96
14	26.81
15	38.29

3.

A professor would like to test the hypothesis that the average number of minutes that a student needs to complete a statistics ex is less than 60 minutes. A random sample of 30 students was selected and the number of minutes needed to complete the ex was recorded. The average time obtained from the 30 students was 64.2 and the sample standard deviation was 10.7 minutes. A significance level of 5% will be used for the hypothesis tet.

What is the value of the statistic t ?