Exercise 12
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Chapter 12
Exercise 12
Part I
1. Since the water in the lake might not be circulating, the algae content of the water at one end
might not be representative of the whole lake. Thus, the sample might be biased.
2. The sample is probably biased. Homeowners in fashionable neighborhoods would be
3. The sample might be biased. Suppose that each box contains 24 cans of fruit and that a
4. According to Table 12.1 the margin of error for a random sample of 600 is four percent.
6. According to Table 12.1, the margin of error for a random sample of 600 is four percent, and
7. Since no mention is made of the size of the sample or of the expected sampling error, the
Exercise 12
11. The conclusion follows only if the average is a mean. If the average is a median, then it
12. The conclusion follows only if the average is a mode, in which case there are more shoes of
13. Since no mention is made of the dispersion, the argument is weak. The rock pile might
14. Since no mention is made of the dispersion, the argument is weak. The class might consist of
15. Since the axes are not scaled, there is no way of knowing how many bugs are killed with one
21. Two percent (4/200) of the group not taking the drug suffered a heart attack, whereas one
Exercise 12
Part II
1. Margin of error = 1.29/√n.
Solving for n, n = (1.29/marg. of error)2
2. mean = 180 3. mean = $40,000 4. mean = 3
5. mean = 3 6. mean = 8
Part III
1. False 6. True 11. False 16. False