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. Center B 140 68.9 3.1 Center A Sample Size Sample Mean (seconds) Sample St. Dev. (seconds) 125 56.5 4.5 a. Using the sample results, develop an 80% 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. Os (4, - 42) sO (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.) O A. The interval means that there is a(n) probability that the difference between the population means is between seconds and seconds. O B. The interval means that, with % confidence, the length of calls in Center A are, on average, between seconds and seconds faster than Center B O C. The interval means that the difference between the sample means will be between seconds and seconds for % of the samples.
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. Center B 140 68.9 3.1 Center A Sample Size Sample Mean (seconds) Sample St. Dev. (seconds) 125 56.5 4.5 a. Using the sample results, develop an 80% 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. Os (4, - 42) sO (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.) O A. The interval means that there is a(n) probability that the difference between the population means is between seconds and seconds. O B. The interval means that, with % confidence, the length of calls in Center A are, on average, between seconds and seconds faster than Center B O C. The interval means that the difference between the sample means will be between seconds and seconds for % of the samples.
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
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Transcribed Image Text: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.
Center A
Center B
Sample Size
Sample Mean (seconds)
Sample St. Dev. (seconds)
125
140
56.5
68.9
4.5
3.1
a. Using the sample results, develop an 80% 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
(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.)
O A. The interval means that there is a(n)
probability that the difference between the population means is between
seconds and
seconds.
O B. The interval means that, with
% confidence, the length of calls in Center A are, on average, between
seconds and
seconds faster than Center B.
O C. The interval means that the difference between the sample means will be between
seconds and
seconds for
% of the samples.
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