Download SHORT ANSWER. Write the word or phrase that best

MA 116 - Chapter 7 review
Name___________________________________
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
For samples of the specified size from the population described, find the mean and standard deviation of the sample
mean x.
1) The National Weather Service keeps records of snowfall in mountain ranges. Records indicate that in a certain
range, the annual snowfall has a mean of 86 inches and a standard deviation of 14 inches. Suppose the
snowfalls are sampled during randomly picked years. For samples of size 49, determine the mean and standard
deviation of x.
2) One barge from Inland Waterways, Inc. can carry a load of 5448.8 lb. Records of past trips show that the
weight of cans that it carries have a mean of 107 lb and standard deviation of 14 lb. For samples of size 49, find
the mean and standard deviation of x.
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
Provide an appropriate response.
3) The mean height for a population is 65 inches and the standard deviation is 3 inches. Let x denote the mean
height for a sample of people picked randomly from the population. True or false, the standard deviation of x
for samples of size 30 is greater than the standard deviation of x for samples of size 20?
4) The mean height for a population is 65 inches. Let x denote the mean height for a sample of people picked
randomly from the population. True or false, the standard deviation of x for samples of size 30 is smaller than
the standard deviation, s, of the population?
5) The mean height for a population is 65 inches and the standard deviation is 3 inches. Let A and B denote the
events described below.
Event A: The height of a randomly selected person will be 5 inches or further from the population mean.
Event B: The mean height of a random sample of 16 people will be 5 inches or further from the population
mean.
True or false, the probability of event A is greater than the probability of event B?
6) The mean height for a population is 65 inches and the standard deviation is 3 inches. Let A and B denote the
events described below.
Event A: The height of a randomly selected person will be within 3 inches of the population mean.
Event B: The mean height of a random sample of 16 people will be within 3 inches of the population mean.
True or false, the probability of event A is greater than the probability of event B?
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7) The mean height for a population is 65 inches and the standard deviation is 3 inches. Let A and B denote the
events described below.
Event A: The mean height of a random sample of 16 people will be within 1 inch of the population mean.
Event B: The mean height of a random sample of 50 people will be within 1 inch of the population mean.
True or false, the probability of event A is greater than the probability of event B?
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
Identify the distribution of the sample mean. In particular, state whether the distribution of x is normal or approximately
normal and give its mean and standard deviation.
8) The weights of people in a certain population are normally distributed with a mean of 150 lb and a standard
deviation of 21 lb. Determine the sampling distribution of the mean for samples of size 9.
9) The mean annual income for adult women in one city is $28,520 and the standard deviation of the incomes is
$5600. The distribution of incomes is skewed to the right. Determine the sampling distribution of the mean for
samples of size 95.
Find the indicated probability or percentage for the sampling error.
10) Scores on an aptitude test are normally distributed with a mean of 220 and a standard deviation of 16.
Determine the percentage of samples of size 4 that have a mean score within 12 points of the population mean
score of 220.
11) The monthly expenditures on food by single adults living in one neighborhood of Los Angeles are normally
distributed with a mean of $370 and a standard deviation of $80. Determine the percentage of samples of size
16 that have a mean expenditure within $36 of the population mean expenditure of $370.
12) The monthly expenditures on food by single adults in one city are normally distributed with a mean of $410
and a standard deviation of $70. What is the probability that the sampling error made in estimating the mean
monthly expenditure of all single adults in that city by the mean of a random sample of 90 such adults will be
at most $10?
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Answer Key
Testname: CHAPTER7.TST
1) Answer:
m x = 86; s x = 2
2) Answer:
m x = 107; s x = 2
3) Answer: FALSE
4) Answer: TRUE
5) Answer: TRUE
6) Answer: FALSE
7) Answer: FALSE
8) Answer: Normal, mean = 150 lb, standard deviation = 7 lb
9) Answer: Approximately normal, mean = $28,520, standard deviation = $575
10) Answer: 86.64%
11) Answer: 92.82%
12) Answer: 0.8262
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