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# Descriptive Statistics and confidence interval

1. A bank located in a commercial district of a city has developed an improved process for serving customers during the noon to 1:00PM peak lunch period. The waiting time (as defined as the time the customer enter the line until he or she is served) of all customers during this hour is recorded over a period of 1 week. A random sample of 15 customers is selected, and the results are as follows:
4.25, 5.55, 3.05, 5.15, 4.75, 2.35, 3.55, 3.20, 4.50, 6.10, 0.40, 5.15, 6.45, 6.20, 3.80
a) Find the sample mean (X) and sample standard deviation (S).
b) Find standard error of the estimator (X). i.e. Standard deviation of X.
c) Set up 95% confidence interval for estimating the average waiting time during peak hour.
d) Interpret the results of part (c) and what are the underlying assumptions that must hold in order to perform the in part (c)?

#### Solution Summary

The solution provides step by step method for the calculation of descriptive statistics . Formula for the calculation and Interpretations of the results are also included.

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