A credit card company operates two customer service centers. Callers to the service centers dial a single number, and a computer program routes callers to the center having the fewest calls waiting. As part of a customer service review program, the credit card center would like to determine whether the average length of a call (not including hold time) is different for the two centers. The managers of the customer service centers are willing to assume that the populations of interest are normally distributed with equal variances. Suppose a random sample of phone calls to the two centers is selected and the results that were reported are shown below. Complete parts a and b. Sample Size Sample Mean (seconds) Sample St. Dev. (seconds) Center A 125 57.2 7.1 Center B 130 73.8 7.5 a. Using the sample results, develop a 98% confidence interval estimate for the difference between the two population means. Let sample 1 be the sample from Center A and let sample 2 be the sample from Center B. _____≤1−2≤_____ (Round to two decimal places as needed.) b. Based on the confidence interval constructed in part a, what can be said about the difference between the average call times at the two centers? (Type integers or decimals rounded to two decimal places as needed. Use ascending order.) A. The interval means that the difference between the sample means will be between seconds and The interval means that there is a(n) population means is between The interval means that, with on average, between B. seconds for % of the samples. probability that the difference between the seconds and seconds. % confidence, the length of calls in Center A are, seconds and seconds faster than Center use excel
A credit card company operates two customer service centers. Callers to the service centers dial a single number, and a computer program routes callers to the center having the fewest calls waiting. As part of a customer service review program, the credit card center would like to determine whether the average length of a call (not including hold time) is different for the two centers. The managers of the customer service centers are willing to assume that the populations of interest are
Sample Size
Sample Mean (seconds) Sample St. Dev. (seconds)
Center A
125 57.2 7.1
Center B
130 73.8 7.5
a. Using the sample results, develop a 98% confidence
_____≤1−2≤_____
(Round to two decimal places as needed.)
b. Based on the confidence interval constructed in part a, what can be said about the difference between the average call times at the two centers?
(Type integers or decimals rounded to two decimal places as needed. Use ascending order.)
A. The interval means that the difference between the sample means will be between
seconds and
-
The interval means that there is a(n) population means is between
-
The interval means that, with on average, between
B.
seconds for % of the samples.
probability that the difference between the seconds and seconds.
% confidence, the length of calls in Center A are, seconds and seconds faster than Center
use excel
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