Answered: During 2011 a company implemented a…

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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Question

During 2011 a company implemented a number of policies aimed at reducing the ages of its customers’ accounts. In order to assess the effectiveness of these measures, the company randomly selects 10 customer accounts. The average age of each account is determined for the years 2010 and 2011. These data are given in Table 10.4. Assuming that the population of paired differences between the average ages in 2011 and 2010 is normally distributed:

Calculate a 95 percent confidence interval for the mean difference in the average account ages between 2010 and 2011. Estimate the minimum reduction in the mean average account ages from 2010 to 2011. (Do not round intermediate calculations. Round your final answers to 4 decimal places. Negative amounts should be indicated by a minus sign.)

Confidence interval = [ , ]

Minimum reduction =

I attached the chart and answered every part of the question except the minimum reduction. Please help.

TABLE 10.4 Average Account Ages in 2010 and 2011
for 10 Randomly Selected Accounts
(for Exercise 10.20) DS AcctAge
Account
1
2
3
4
5
6
7
8
9
10
Average Age of
Account in 2011
(Days)
27
19
40
30
33
25
31
29
15
21
Mean
Variance
Observations
Pearson Correlation
Hypothesized Mean
Average Age of
Account in 2010
(Days)
FIGURE 10.10 Excel Output of a Paired Difference Analysis of the Account Age Data (for Exercise 10.20)
t-Test: Paired Two Sample for Means
2011 Age
27
53.55556
10
df
t Stat
P(T<=t) one-tail
35
24
47
28
41
33
35
51
18
28
0.804586
0
9
-3.61211
0.00282
2010 Age
34
104.2222
10

Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.

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