Question

A sample of 100 bank customer waiting times are given in the following table:

The mean and the standard deviation of the sample of 100 bank customer waiting times are x¯x¯ = 6.139 and s = 2.641.
   

(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?   

It (Click to select)isis not somewhat reasonable.

(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. (Round your answers to 3 decimal places. Negative amounts should be indicated by a minus sign.)

[x¯x¯ ± s]	[, ]
[x¯x¯ ± 2s]	[, ]
[x¯x¯ ± 3s]	[, ]

(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 9 minutes for service?

    
(Click to select)YesNo , because the upper limit of the (Click to select)95.4468.2699.73 % interval is
(Click to select)less thangreater thanequal to 9 minutes.    

(d) How do the percentages of the 100 waiting times that actually fall into the intervals [x¯x¯ ± s], [x¯x¯ ± 2s], and [x¯x¯ ± 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? (Round your answers to the nearest whole number. Omit the "%" sign in your response.)    

% fall into [x¯x¯ ± s],  % fall into [x¯x¯ ± 2s],  % fall into [x¯x¯ ± 3s].

(Click to select)YesNo, they (Click to select)areare not reasonably valid.

Answer 1