A customer service department asks its customers to rate their over-the-phone service on a scale of 1-20 immediately after their service has been completed. The department then matches each customer's rating with the number of minutes the person waited on hold. The accompanying table shows the ratings and number of minutes on hold for 10 randomly selected customers. Minutes Rating 4 16 9 13 0 19 5 11 7 14 2 15 9 14 4 20 8 15 4 12
A customer service department asks its customers to rate their over-the-phone service on a scale of 1-20 immediately after their service has been completed. The department then matches each customer's rating with the number of minutes the person waited on hold. The accompanying table shows the ratings and number of minutes on hold for 10 randomly selected customers. Minutes Rating 4 16 9 13 0 19 5 11 7 14 2 15 9 14 4 20 8 15 4 12
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
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A customer service department asks its customers to rate their over-the-phone service on a scale of 1-20 immediately after their service has been completed. The department then matches each customer's rating with the number of minutes the person waited on hold. The accompanying table shows the ratings and number of minutes on hold for 10 randomly selected customers.
Minutes | Rating |
4 | 16 |
9 | 13 |
0 | 19 |
5 | 11 |
7 | 14 |
2 | 15 |
9 | 14 |
4 | 20 |
8 | 15 |
4 | 12 |
Construct a 95% confidence interval for the average rating given by a customer who waits 14 minutes.
UCL=
LCL=
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I already tried this answer and it was wrong. I will attach an image of the example that is given. I do not know how they used excel to do this.

Transcribed Image Text:c. Construct a 95% confidence interval for the average rating given by a customer that waits 1 minute.
The formula for the confidence interval is given below, where y is the predicted value of y for the given value of x, t,/2
is the critical t-statistic from the Student's t-distribution with n- 2 degrees of freedom, s, is the
standard error of the estimate, x is the average value of x from the sample, and n is the number of ordered pairs.
(x-x)²
1
+
(Ex)*
(Ex²) -
While technology or the formula can be used to find the confidence interval, in this problem, technology will be used. Before the confidence interval can be found, a few other calculations need to be done. The formula
for y is given below, where bo is the y-intercept, b, is the slope, and x is the given value of x.
y = bo + b,x
Substitute the values x = 1, bo = 16.5662, and b,
= - 0.3010 into the formula and simplify, rounding to three decimal places as needed.
= bo + b,x
= 16.5662 + (-0.3010) • 1
Substitute.
= 16.265
Use technology to find the lower limit, rounding to two decimal places.
LCL = 11.32
Use technology to find the upper limit, rounding to two decimal places.
UCL = 21.21
Therefore, the 95% confidence interval for the average rating given by a customer who waits 1 minute has a lower limit of 11.32 and an upper limit of 21.21.
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