THE TRASH BAG CASE DS TrashBag
The mean and the standard deviation of the sample of 40 trash bag breaking strengths are
x = 50.575 and s = 1.6438.
a What does the histogram in Figure 2.17 (page 53) say about whether the Empirical Rule should be used to describe the trash bag breaking strengths?
|
Rank
|
Team
|
Value ($mil)
|
Revenue ($mil)
|
|
1
|
Hendrick Motorsports
|
350
|
177
|
|
2
|
Roush Fenway
|
224
|
140
|
|
3
|
Richard Childress
|
158
|
90
|
|
4
|
Joe Gibbs Racing
|
152
|
93
|
|
5
|
Penske Racing
|
100
|
78
|
|
6
|
Stewart-Haas Racing
|
95
|
68
|
|
7
|
Michael Waltrip Racing
|
90
|
58
|
|
8
|
Earnhardt Ganassi Racing
|
76
|
59
|
|
9
|
Richard Petty Motorsports
|
60
|
80
|
|
10
|
Red Bull Racing
|
58
|
48
|
b Use the Empirical Rule to calculate estimates of tolerance intervals containing 68.26 percent,
95.44 percent, and 99.73 percent of all possible trash bag breaking strengths.
c Does the estimate of a tolerance interval containing 99.73 percent of all breaking strengths provide evidence that almost any bag a customer might purchase will have a breaking strength that exceeds 45 pounds? Explain your answer.
d 
How do the percentages of the 40 breaking strengths in Table 1.9 (page 14) that actually fall into the intervals [x ±s], [x ± 2s], and [x ± 3s] compare to those given by the Empirical Rule? Do these comparisons indicate that the statistical inferences you made in parts b and c are reasonably valid?