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CHAPTER 2
A REVIEW OF BASIC STATISTICAL CONCEPTS
ANSWERS TO PROBLEMS AND CASES
1. Descriptive Statistics
Variable N Mean Median StDev SE Mean
Orders 28 21.32 17.00 13.37 2.53
Variable Min Max Q1 Q3
Orders 5.00 54.00 11.25 28.75
e. If the change causes all customers to consolidate a number of small orders into
2. Descriptive Statistics
Variable N Mean Median StDev SE Mean
X
b. 1 = .95 Z = 1.96, n = 30,
71.13,76.10
SX
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d. We see that the 95% confidence intervals in b and c are not much different
59.10241.23
5. H0: = 12.1 n = 100 = .05
increased.
6. point estimate: 8.1 seats
7. n = 60,
87.,60.5
SX
1
9.560.5
9.5
X
3
8. df = n 1 = 14 1 = 13,
52.,31.4
SX
9. H0: = 700 n = 50 = .05
700715
10. This problem can be used to illustrate how a random sample is selected with Minitab. In
order to generate 30 random numbers from a population of 200 click the following menus:
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11. a.
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12. a.
c. Y = 2312 Y2 = 515,878 X = 53.7
13. This is a good population for showing how random samples are taken. If three-digit
random numbers are generated from Minitab as demonstrated in Problem 10, the selected
14. a.
15. n = 175,
3.10,2.45
SX
Hypothesis test:
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700,63:
0
H
17. Large sample 95% confidence interval for mean monthly return
18. a.
b. r = .581, positive linear association between wages and length of service.
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CASE 2-1: ALCAM ELECTRONICS
In our consulting work, business people sometimes tell us that business schools teach a risk-
taking attitude that is too conservative. This is often reflected, we are told, in students choosing too
CASE 2-2: MR. TUX
In this case, John Mosby tries some primitive ways of forecasting his monthly sales. The
things he tries make some sort of sense, at least for a first cut, given that he has had no formal
training in forecasting methods. Students should have no trouble finding flaws in his efforts, such
as:
1. The mean value for each year, if projected into the future, is of little value since
month-to-month variability is missing.
CASE 2-3: ALOMEGA FOOD STORES
r-squared value of 36% is not very high. Using more predictor variables, along with examining