The mean and the standard deviation of the sample of 100 bank customer waiting times are and

Question:

The mean and the standard deviation of the sample of 100 bank customer waiting times are and = 42.95 and s = 2.475.
a. What does the histogram in Figure 2.16 say about whether the Empirical Rule should be used to describe the bank customer waiting times?
b. Use the Empirical Rule to calculate estimates of tolerance intervals containing 68.26 percent, 95.44 percent, and 99.73 percent of all possible bank customer waiting times.
c. Does the estimate of a tolerance interval containing 68.26 percent of all waiting times provide evidence that at least two-thirds of all customers will have to wait less than eight minutes for service? Explain your answer.
d. How do the percentages of the 100 waiting times in Table 1.8 that actually fall into the intervals, [± s], [2s], and [± 3s] compare to those given by the Empirical Rule?
Do these comparisons indicate that the statistical inferences you made in parts b and c are reasonably valid?
Figure 2.16