1. Chapter 7: Sampling Distributions
Chapter 7 Reflection
The Practice of Statistics, 4th edition – For AP*
STARNES, YATES, MOORE

2. Chapter 7 Test Recap: #1 Multiple Choice – Answer D
1. A survey conducted by Black Flag asked whether or not the action of a certain type of roach disk was effective in killing roaches. 79% of the respondents agreed that the roach disk was effective. The number 79% is a
(A.) parameter.
(B.) population.
(C.) sampling distribution.
(D.) statistic
(E.) sample

3. Chapter 7 Test Recap: #2 Multiple Choice – Answer A
2. Below are dot plots of the values taken by three different statistics in 30 samples from the same population. The true value of the population parameter is marked with an arrow. The statistic that has the largest bias among these three is
(A) statistic A.
(B) statistic B.
(C ) statistic C.
(D) A and B have similar bias, and it is larger than the bias of C.
(E)B and C have similar bias, and it is larger than the bias of A.

4. Chapter 7 Test Recap: #3 Multiple Choice – Answer C
3. If we took a SRS of 1700 people from California (population 34 million) and a SRS of 1000 people from Detroit (population 1 million) which sampling distribution would have the smaller standard deviation?
(A.) Detroit, because 1000/1,000,000 is more than 1700/32,000,000.
(B.) Detroit, because it has the smaller population.
(C.) California, because the sample size (1700) is larger than for Detroit (1000).
(D.) California, because it has the larger population.
(E.) Both would be the same, because simple random samples (SRS) are taken in both places.

5. Chapter 7 Test Recap: #4 & #5 Multiple Choice – Answers C & D
A 2010 study of 240 randomly-selected residents of a subtropical resort city with 82,000 residents found that 5.4% of them had been exposed to the mosquito-borne virus that causes Dengue fever. Suppose the actual percentage of people in the city who have been exposed to the virus is 3%. Let p = the proportion of residents who have been exposed in a random sample of 240,
4. The standard deviation of p is approximately
(A.)
(B.)
(C.)
(D.)
(E.)
5. Which of the following conditions had to be met in order for us to use the formula for that we used in the previous question?
(A.) n ≥ 30
(B.) np(1-p) ≥ 10
(C.) np ≥10 and n(1-p) ≥ 10
(D.) n < 0.10N
(E.)The population distribution is approximately Normal.

6. Chapter 7 Test Recap: #6 Multiple Choice Answer: 30 ≤ n ≤ 75
6.The histogram below was obtained from data on 750 high school basketball games in a regional athletic conference. It represents the number of three-point baskets made in each game.
What is the range of sample sizes the research could take from this population without violating conditions required for the application of the formula and the central limit theorem?

7. Chapter 7 Test Recap: #7 Multiple Choice – Answer B
7. A factory produces plate glass with a mean thickness of 4 mm and a standard deviation of 1.1 mm. A simple random sample of 100 sheets of glass is to be measured, and the sample mean thickness of the 100 sheets is to be computed.
We know the random variable has approximately a normal distribution because of the
(A.)
law of large numbers.
(B.)
central limit theorem.
(C.)
law of proportions.
(D.)
fact that probability is the long run proportion of times an event occurs.
(E.)
normality of the population distribution.

8. Chapter 7 Test Recap: #8 Multiple Choice – Answer C
8. In a large population of adults, the mean IQ is 112 with a standard deviation of 20. Suppose 200 adults are randomly selected for a market research campaign. The sampling distribution of the sample mean IQ is
(A.)
exactly Normal, mean 112, standard deviation 20.
(B.)
approximately Normal, mean 112, standard deviation 0.1.
(C.)
approximately Normal, mean 112, standard deviation
(D.)
approximately Normal, mean 112, standard deviation 20.
(E.)
exactly Normal, mean 112, standard deviation

9. Chapter 7 Test Recap: #9 Multiple Choice – Answer B
9. A census of the labor force in a large metropolitan area found that the time it takes for people to commute to work has a mean of 20.5 minutes and a standard deviation of 15.4 minutes. Which of the following represents the probability that a random sample of 40 people have a mean commute time that is greater than 25 minutes?
(A.)
(B.)
(C.)
(D.)
(E.)

10. Chapter 7 Test Recap: #10 Multiple Choice – Answer D
10. A survey asks a random sample of 500 adults in Ohio if they support an increase in the state sales tax from 5% to 6%, with the additional revenue going to education. Let denote the proportion in the sample who say they support the increase. Suppose that 53% of all adults in Ohio support the increase. What is the correct notation and probability that less than half the sample will say they support the increase? A. B. C. D. E.

11.   For each description below, identify each underlined number as a parameter or statistic. Use appropriate notation to describe each number, e.g., = 0.96.

12. 12.Suppose two different statistics—call them Statistic A and Statistic B—can be used to estimate the same population parameter. Statistic A has lower bias than B, and A also has low variability compared to B. On the two axes below, draw two parallel dotplots showing 8 values of each statistic that are consistent with these characteristics. Assume that the parameter value is at the arrow on the axes.