7.1 solutions - DO NOT POST THESE ANSWERS ONLINE BFW...

DO NOT POST THESE ANSWERS ONLINE © BFW Publishers 2014
Chapter 7: Sampling Distributions
Chapter 7
Section 7.1
Check Your Understanding, page 425:
1. The parameter is 20 μ = ounces of iced tea. The statistic is 19.6 x = ounces of iced tea.
2. The parameter is
0.10, p =
or 10% of passengers. The statistic is
ˆ
0.08, p = or 8% of the
sample of passengers.
Check Your Understanding, page 428:
1. The individuals are the M&M’S Milk Chocolate Candies, the variable is the color of the
M&M, and the parameter of interest is the proportion of orange M&M’S. The graph below
shows the population distribution.
2. The graph below shows a possible distribution of sample data. For this sample there are 11
orange M&M’S so
11
ˆ
0.22.
50
p = =
3. The middle graph is the approximate sampling distribution of ˆ. p The statistic measures the
proportion of orange candies in samples of 50 M&M’S. Assuming that the company is correct,
20% of the M&M’S are orange, so the center of the distribution of ˆ p should be at approximately
0.20. The first graph shows the distribution of the colors for one sample, rather than the
distribution of ˆ p from many samples, and the third graph is centered at 0.40 rather than 0.20.

DO NOT POST THESE ANSWERS ONLINE © BFW Publishers 2014
The Practice of Statistics for 5/e
Check Your Understanding, page 434:
1. The median does not appear to be an unbiased estimator of the population median. The mean
of the approximate sampling distribution of the sample median (73.5) is not equal to the median
of the population (75).
2. Increasing the sample size from 10 to 20 will decrease the spread of the sampling distribution.
Larger samples provide more precise estimates because larger samples include more information
about the population distribution.
3. The sampling distribution of the sample median is skewed to the left and unimodal.
Exercises, page 436:
7.1 (a) Population : all people who signed a card saying that they intend to quit smoking.
Parameter : the proportion of the population who actually quit smoking. Sample : a random
sample of 1000 people who signed the cards. Statistic : the proportion of the sample who actually
quit smoking; ˆ 0.21. p =
(b) Population : all the turkey meat. Parameter : minimum temperature in all of the turkey meat.
Sample : four randomly chosen locations in the turkey. Statistic : minimum temperature in the
sample of four locations; sample minimum =
170 F. o
7.2 (a) Population : individuals in U.S. households. Parameter : proportion of the U. S.