Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Provide an appropriate response.
1)
A magazine poll of unemployed men in the U.S. stated “22% of those polled suffer from clinical
depression; the margin of error for the poll is plus or minus 6 percentage points.” How would you
interpret this statement? Assume that the margin of error is associated with a 95% confidence
interval.
1)
A)
There is a 95% chance that the percentage of all unemployed men in the U.S. who suffer from
clinical depression is somewhere between 16% and 28%.
B)
We can be 95% confident that the percentage of all unemployed men in the U.S. who suffer
from clinical depression is somewhere between 16% and 28%.
C)
A confidence interval for the percentage of all unemployed men in the U.S. who suffer from
clinical depression is 17% to 27%. There is a 6% chance that this interval does not include the
population proportion, p.
D)
The percentage of all unemployed men in the U.S. who suffer from clinical depression is 22%.
The chance that this estimate is incorrect is 6%
2)
The college daily reported: “300 students living in university housing were polled. 180 said that
they were satisfied with their living conditions. Based on this survey we conclude that 60% of
students living in dormitories are satisfied. The margin of error of the study is ±6 percentage
points (with a 95% degree of confidence). Which statement is correct?
2)
A)
There is not enough information to determine whether the margin of error is consistent with
the sample size.
B)
The stated margin of error could have been achieved with a smaller sample size.
C)
A larger sample should be used to achieve the stated margin of error.
D)
The margin of error is consistent with the sample size.
3)
In a poll of 2490 voters in a certain city, 71% said that they backed a bill which would limit growth
and development in their city. The margin of error in the poll was reported as 2 percentage points
(with a 95% degree of confidence). Which statement is correct?
3)
A)
There is not enough information to determine whether the margin of error is consistent with
the sample size
B)
The reported margin of error is consistent with the sample size
C)
The stated margin of error could be achieved with a smaller sample size
D)
The sample size is too small to achieve the stated margin of error
4)
In a poll of 2500 voters in a certain city, 64% said that they backed a bill which would limit growth
and development in their city. The margin of error in the poll was reported as 2 percentage points
(with a 95% degree of confidence). Which statement is correct?
4)
A)
There is not enough information to determine whether the margin of error is consistent with
the sample size
B)
The reported margin of error is consistent with the sample size
C)
For the given sample size, the margin of error should be smaller than stated
D)
The sample size is too small to achieve the stated margin of error
5)
A researcher is interested in estimating the proportion of voters who favor a tax on e–commerce.
Based on a sample of 250 people, she obtains the following 99% confidence interval for the
population proportion p:
0.113 < p < 0.171
Which of the statements below is a valid interpretation of this confidence interval?
5)
A)
If 100 different samples of size 250 were selected and, based on each sample, a confidence
interval were constructed, exactly 99 of these confidence intervals would contain the true
value of p.
B)
There is a 99% chance that the true value of p lies between 0.113 and 0.171
C)
If many different samples of size 250 were selected and, based on each sample, a confidence
interval were constructed, in the long run 99% of the confidence intervals would contain the
true value of p.
D)
If many different samples of size 250 were selected and, based on each sample, a confidence
interval were constructed, 99% of the time the true value of p would lie between 0.113 and
0.171
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
6)
A researcher obtained independent random samples of men and women between the ages
of 20 and 29. She finds that 35 of 410 men and 59 of 398 women suffered from insomnia at
least once a week during the past year. Decide whether or not the conditions and
assumptions for inference with the two–proportions z–test are satisfied. Explain your
answer.
6)
Use the one–proportion z–test to perform the required hypothesis test. Use the critical–value approach.
7)
A manufacturer considers his production process to be out of control when defects exceed
3%. In a random sample of 85 items, the defect rate is 5.9% but the manager claims that this
is only a sample fluctuation and that production is not really out of control. At the 0.01
level of significance, do the data provide sufficient evidence that the percentage of defects
exceeds 3%?
7)
Use the one–proportion z–test to perform the required hypothesis test. Use the P–value approach.
8)
A poll of 1000 adult Americans reveals that 48% of the voters surveyed prefer the
Democratic candidate for the presidency. At the 0.05 level of significance, do the data
provide sufficient evidence to conclude that the percentage of voters who prefer the
Democrat is less than 50%?
8)
Provide an appropriate response.
9)
A researcher wishes to determine whether the proportion of American women who smoke
differs from the proportion of American men who smoke. He wants to test the hypothesis
H0: p1=p2 where p1 represents the proportion of American women who smoke and p2
represents the proportion of American men who smoke. He randomly selects 100 married
couples. Among the 100 women in the sample are 21 smokers. Among the 100 men are 29
smokers. Are the assumptions for a two–proportions z–test satisfied? If not, which
assumption is violated and why?
9)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the P–value approach.
10)
A marketing survey involves product recognition in New York and California. Of 558 New
Yorkers surveyed, 193 recognized the product while 196 out of 614 Californians recognized
the product. At the 5% significance level, do the data provide sufficient evidence to
conclude that the recognition rate in New York differs from the recognition rate in
California?
10)
Provide an appropriate response.
11)
In a random sample of 500 people aged 20–24, 22% were smokers. In a random sample of
450 people aged 25–29, 14% were smokers. A 95% confidence interval for the difference
between the proportions of 20–24 year olds and 25–29 year olds who are smokers is 0.032
to 0.128. Give an interpretation of this confidence interval.
11)
12)
Let p1 represent the proportion of men in a city who are unemployed and let p2 represent
the proportion of women in the same city who are unemployed. A 95% confidence interval
for p1–p2 is from –0.05 to –0.03. Give an interpretation of this confidence interval.
12)
Use the one–proportion z–test to perform the required hypothesis test. Use the critical–value approach.
13)
In a sample of 80 adults selected randomly from one town, it is found that 8 of them have
been exposed to a particular strain of the flu. At the 0.01 significance level, test whether the
proportion of all adults in the town that have been exposed to this strain of the flu differs
from the nationwide percentage of 8%.
13)
Provide an appropriate response.
14)
^ ^
In the context of a two–proportions z–test, explain what each of the following symbols
represents: x1, n1, p1, p1, pp.
14)
15)
Suppose the proportion of women who follow a regular exercise program is pw and the
proportion of men who follow a regular exercise program is pm. A study found a 98%
confidence interval for pw–pm to be (–0.023, 0.114). Does this study provide evidence
that the proportion of women who exercise is different from the proportion of men who
exercise? Explain.
15)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the critical–value approach.
16)
A researcher finds that of 1000 people who regularly attend a religious service, 31 would
stop to help a person with car trouble. Of 1200 people interviewed who do not regularly
attend a religious service, 22 would stop to help a person with car trouble. At the 0.05
significance level, do the data provide sufficient evidence to conclude that those who
regularly attend a religious service are more likely to stop and help a person with car
trouble?
16)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the P–value approach.
17)
In a random sample of 500 people aged 20–24, 22% were smokers. In a random sample of
450 people aged 25–29, 14% were smokers. Do the data provide sufficient evidence to
conclude that the proportion of smokers in the 20–24 age group is different from the
proportion of smokers in the 25–29 age group? Use a significance level of 0.01.
17)
Use the one–proportion z–test to perform the required hypothesis test. Use the P–value approach.
18)
In a clinical study of an allergy drug, 108 of the 201 subjects reported experiencing
significant relief from their symptoms. At the 0.01 significance level, do the data provide
sufficient evidence to conclude that more than half of those using the drug experience
relief?
18)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the critical–value approach.
19)
A random sampling of sixty pitchers from the National League and fifty–two pitchers from
the American League showed that 16 National and 8 American League pitchers had
E.R.A’s below 3.5. At the 1% significance level, do the data provide sufficient evidence to
conclude that the proportion of National League pitchers with E.R.A’s below 3.5 differs
from the proportion of American League pitchers with E.R.A’s below 3.5 ?
19)
Provide an appropriate response.
20)
A congressman wants to measure the level of support in his district for campaign finance
reform and wants to determine whether there is a gender gap with respect to this issue.
One researcher suggests that they find separate confidence intervals for the percent of men
and the percent of women who favor reform and then see if the intervals overlap. Another
researcher suggests that they find a confidence interval for the difference in the proportions
of men and women who favor reform. Which is the correct approach? Why?
20)
21)
What is the null hypothesis for the two–proportions z–test? What assumptions are
required for this test?
21)
22)
Suppose the proportion of sophomores at a particular college who purchased used
textbooks in the past year is ps and the proportion of freshmen at the college who
purchased used textbooks in the past year is pf. A study found a 98% confidence interval
for ps–pf to be (0.234, 0.423). Does this interval suggest that sophomores are more likely
than freshmen to buy used textbooks? Explain.
22)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the critical–value approach.
23)
Use the given sample data to test the claim that p1< p2. Use a significance level of 0.10.
Sample 1 Sample 2
n1= 462 n2= 380
x1= 84 x2 = 95
23)
Provide an appropriate response.
24)
For what kinds of data might you be interested in conducting inferences for a population
proportion and for what kinds of data might you be interested in conducting inferences for
a population mean? Explain how you distinguish the two types of data and give an
example of each type of data.
24)
25)
Give an example of a situation in which you might wish to use the two–proportions z–test.
Identify the two populations in your example and the attribute of interest. State what you
would wish to determine by performing the hypothesis test and write the hypotheses.
25)
Use the one–proportion z–test to perform the required hypothesis test. Use the P–value approach.
26)
In a sample of 165 children selected randomly from one town, it is found that 30 of them
suffer from asthma. At the 0.05 significance level, do the data provide sufficient evidence
to conclude that the percentage of all children in the town who suffer from asthma is
different from 11%?
26)
Provide an appropriate response.
27)
^
^
A population consists of four men and one woman. The first names of the men are Adam,
Bernard, Charlie, and Daniel. The first name of the woman is Elena. Suppose that the
specified attribute is “male”. a. Determine the population proportion, p.
b. Complete the table below. The first column shows the possible samples of size 3, the
second column gives the number of successes – the number of males obtained – for each
sample, and the third column shows the sample proportion.
Sample Number of males Sample proportion
x p
A, B, C 3 1
A, B, D 3 1
A, B, E 2 2/3
A, C, D
A, C, E
A, D, E
B, C, D
B, C, E
B, D, E
C, D, E
c. Use the third column of the table to obtain the mean of the variable p. Is this mean
27)
8
smaller, larger, or the same as your answer in part a?. Why is this the case?
28)
A mayoral election race is tightly contested. In a random sample of 1500 likely voters, 795
said that they were planning to vote for the current mayor. Based on this sample, would
you claim that the mayor will win a majority of the votes? Explain.
28)
Use the one–proportion z–test to perform the required hypothesis test. Use the P–value approach.
29)
A supplier of 3.5″ disks claims that no more than 1% of the disks are defective. In a random
sample of 600 disks, it is found that 3% are defective, but the supplier claims that this is
only a sample fluctuation. At the 0.01 level of significance, do the data provide sufficient
evidence that the percentage of defects exceeds 1%?
29)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the P–value approach.
30)
Use the given sample data to test the claim that p1< p2. Use a significance level of 0.10.
Sample 1 Sample 2
n1= 462 n2= 380
x1= 84 x2 = 95
30)
Use the one–proportion z–test to perform the required hypothesis test. Use the P–value approach.
31)
An article in a journal reports that 34% of American fathers take no responsibility for child
care. A researcher claims that the figure is higher for fathers in the town of Littleton. A
random sample of 233 fathers from Littleton yielded 96 who did not help with child care.
Do the data provide sufficient evidence to conclude that in Littleton the percentage of
fathers who take no responsibility for child care is higher than 34%? Use a 0.05
significance level.
31)
32)
A research group claims that less than 28% of students at one medical school plan to go
into general practice. It is found that among a random sample of 120 of the school’s
students, 20% of them plan to go into general practice. At the 0.10 significance level, do the
data provide sufficient evidence to conclude that the percentage of all students at this
school who plan to go into general practice is less than 28%?
32)
Provide an appropriate response.
33)
^
^
Suppose that a population consists of 30 men and 50 women. Let p represent the
proportion of women in a random sample of size 10 from this population. What is the
mean of p for all possible samples of size 10 from this population?
33)
Use the one–proportion z–test to perform the required hypothesis test. Use the critical–value approach.
34)
In a clinical study of an allergy drug, 110 of the 210 subjects reported experiencing
significant relief from their symptoms. At the 0.01 significance level, do the data provide
sufficient evidence to conclude that a majority of all those using the drug experience relief?
34)
35)
An airline’s public relations department says that the airline rarely loses passengers’
luggage. It further claims that on those occasions when luggage is lost, 88% is recovered
and delivered to its owner within 24 hours. A consumer group who surveyed a large
number of air travelers found that only 133 out of 160 people who lost luggage on that
airline were reunited with the missing items by the next day. At the 5% level of
significance, do the data provide sufficient evidence to conclude that the proportion of
times that luggage is returned within 24 hours is less than 0.88?
35)
Provide an appropriate response.
36)
A researcher wishes to test whether the rate of defectives among computers from
manufacturer A differs from the rate of defectives among computers from manufacturer B.
She selects two independent random samples and finds that 1.5% of 200 computers from
manufacturer A are defective and 3.5% of 400 computers from manufacturer B are
defective.
Are the conditions and assumptions for inference with the two–proportion z–test
satisfied? Explain your answer.
36)
Use the one–proportion z–test to perform the required hypothesis test. Use the critical–value approach.
37)
A research group claims that fewer than 28% of students at one medical school plan to go
into general practice. It is found that among a random sample of 130 of the school’s
students, 20% of them plan to go into general practice. At the 0.10 significance level, test
the research group’s claim.
37)
Provide an appropriate response.
38)
A researcher is interested in estimating the proportion of adults in the U.S. who suffer from
a rare form of cancer. In a random sample of 1000 adults in the U.S. she finds that 0.3%
suffer from this form of cancer. She then obtains the following 90% confidence interval:
0.003 ± 1.645 (0.003)(0.997)/1000
or 0.000155 to 0.0058
She concludes that she can be 90% confident that the true proportion of adults in the U.S.
suffering from this form of cancer is somewhere between 0.0155% and 0.58%. Is anything
wrong with this reasoning? Explain your answer.
38)
Use the one–proportion z–test to perform the required hypothesis test. Use the critical–value approach.
39)
In a sample of 151 children selected randomly from one town, it is found that 34 of them
suffer from asthma. At the 0.05 significance level, do the data provide sufficient evidence
to conclude the proportion of all children in the town who suffer from asthma is different
from 11%?
39)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the critical–value approach.
40)
7 of 8500 people vaccinated against a certain disease later developed the disease. 18 of
10,000 people vaccinated with a placebo later developed the disease. At the 2%
significance level, do the data provide sufficient evidence to conclude that those who are
vaccinated against the disease are at lower risk of developing the disease than those
vaccinated with a placebo?
40)
Use the one–proportion z–test to perform the required hypothesis test. Use the critical–value approach.
41)
In 2000, the percentage of adults in a certain town who drove an SUV was 53%. In 2005, in
a random sample of 100 people from this town, 45% said that they drive an SUV. At the
10% level of significance, do the data provide sufficient evidence to conclude that the
percentage of adults in this town who drive an SUV has changed from the 2000 percentage
of 53%?
41)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the P–value approach.
42)
Of 85 randomly selected women, 38 have tried some form of alternative medicine. Of 90
randomly selected men, 23 have tried some form of alternative medicine. At the 1%
significance level, do the data provide sufficient evidence to conclude that women are
more likely than men to try alternative forms of medicine?
42)
Use the one–proportion z–test to perform the required hypothesis test. Use the P–value approach.
43)
In a sample of 88 adults selected randomly from one town, it is found that 6 of them have
been exposed to a particular strain of the flu. At the 0.01 significance level, do the data
provide sufficient evidence to conclude that the percentage of all adults in the town that
have been exposed to this strain of the flu differs from the nationwide percentage of 8%?
43)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the P–value approach.
44)
In a random sample of 360 women, 65% favored stricter gun control laws. In a random
sample of 220 men, 60% favored stricter gun control laws. At the 0.05 significance level, do
the data provide sufficient evidence to conclude that the proportion of women favoring
stricter gun control is higher than the proportion of men favoring stricter gun control?
44)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the critical–value approach.
45)
A report on the nightly news broadcast stated that 14 out of 115 households with pet dogs
were burglarized and 23 out of 205 without pet dogs were burglarized. At the 5%
significance level, do the data provide sufficient evidence to conclude that households with
pet dogs are at less risk of being burglarized?
45)
46)
A marketing survey involves product recognition in New York and California. Of 558 New
Yorkers surveyed, 193 recognized the product while 196 out of 614 Californians recognized
the product. At the 5% significance level, do the data provide sufficient evidence to
conclude that the recognition rate in New York differs from the recognition rate in
California?
46)
47)
Of 85 randomly selected women, 38 have tried some form of alternative medicine. Of 90
randomly selected men, 23 have tried some form of alternative medicine. At the 1%
significance level, do the data provide sufficient evidence to conclude that women are
more likely than men to try alternative forms of medicine?
47)
48)
In a random sample of 500 people aged 20–24, 22% were smokers. In a random sample of
450 people aged 25–29, 14% were smokers. Do the data provide sufficient evidence to
conclude that the proportion of smokers in the 20–24 age group is different from the
proportion of smokers in the 25–29 age group? Use a significance level of 0.01.
48)
Use the one–proportion z–test to perform the required hypothesis test. Use the critical–value approach.
49)
An article in a journal reports that 34% of American fathers take no responsibility for child
care. A researcher claims that the figure is higher for fathers in the town of Littleton. A
random sample of 238 fathers from Littleton yielded 95 who did not help with child care.
Do the data provide sufficient evidence to conclude that in Littleton the proportion of
fathers who take no responsibility for child care.is higher than 0.34? Use a 0.05 significance
level.
49)
50)
A poll of 1,068 adult Americans reveals that 48% of the voters surveyed prefer the
Democratic candidate for the presidency. At the 0.05 level of significance, do the data
provide sufficient evidence that the percentage of all voters who prefer the Democrat is
less than 50%?
50)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the P–value approach.
51)
A researcher finds that of 1000 people who regularly attend a religious service, 31 would
stop to help a person with car trouble. Of 1200 people interviewed who do not regularly
attend a religious service, 22 would stop to help a person with car trouble. At the 0.05
significance level, do the data provide sufficient evidence to conclude that those who
regularly attend a religious service are more likely to stop and help a person with car
trouble?
51)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the critical–value approach.
52)
In a random sample of 360 women, 65% favored stricter gun control laws. In a random
sample of 220 men, 60% favored stricter gun control laws. At the 0.05 significance level, do
the data provide sufficient evidence to conclude that the proportion of women favoring
stricter gun control is higher than the proportion of men favoring stricter gun control?
52)
Provide an appropriate response.
53)
According to a magazine article, 34% of married men in the U.S. are dissatisfied with their
marriage. Under what circumstances is the proportion 0.34 a population proportion? a
sample proportion?
53)
54)
^
A (1 –)–level confidence interval for a population proportion that has a margin of error
of at most E can be obtained by choosing
n = 0.25 z/2
E
2
rounded up to the nearest whole number.
Explain why, if p is not equal to 0.5, this will result in a larger sample size than needed to
obtain the required margin of error.
54)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the P–value approach.
55)
7 of 8500 people vaccinated against a certain disease later developed the disease. 18 of
10,000 people vaccinated with a placebo later developed the disease. At the 2%
significance level, do the data provide sufficient evidence to conclude that those who are
vaccinated against the disease are at lower risk of developing the disease than those
vaccinated with a placebo?
55)
Use the two–proportions z–test to perform the required hypothesis test. Assume that independent simple random
samples have been selected from the two populations. Use the critical–value approach.
56)
In a survey, 72 of 195 college graduates said that they were satisfied in their work, while 65
of 185 adults without a college education said that they were satisfied with their work. At
the 5% significance level, do the data provide sufficient evidence to conclude that college
graduates are more likely to be satisfied with their work than those without a college
education?
56)
Provide an appropriate response.
57)
A poll investigating the level of public support for proposed gun control legislation
reported that 76% of the respondents were in favor. The pollsters reported a sampling
error of ±2%. When the responses were broken down by gender, support was 3% higher
among women than men. The pollsters said the margin of error for this difference was ±
3%. Why is the margin of error larger for the difference in support between the genders
than for the overall level of support?
57)
58)
A mayoral election race is tightly contested. In a random sample of 2200 likely voters, 1144
said that they were planning to vote for the current mayor. Based on this sample, would
you claim that the mayor will win a majority of the votes? Explain.
58)
59)
A researcher wishes to test whether there is a difference between the proportions of
women and men who favor stricter gun control legislation. In a random sample of 300
women, 68% favored stricter gun control legislation. In a random sample of 200 men, 59%
favored stricter gun control legislation. Identify the specified attribute. Determine, if
possible, the two sample proportions. If it is not possible to determine the sample
proportions, explain why not. Determine, if possible, the two population proportions. If it
is not possible to determine the population proportions, explain why not.
59)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Find the P–value for the indicated hypothesis test.
60)
In a sample of 88 children selected randomly from one town, it is found that 8 of them suffer from
asthma. Find the P–value for a hypothesis test to determine whether the proportion of all children
in the town who suffer from asthma differs from 11%.
60)
A)
0.5686
B)
0.2157
C)
0.2843
D)
0.7157
The number of successes and the sample size are given for a simple random sample from a population. Use the
one–proportion z–interval procedure to find the required confidence interval.
61)
n =66, x =12; 95% level
61)
A)
0.103 to 0.261
B)
0.089 to 0.275
C)
0.104 to 0.260
D)
0.088 to 0.276
Use the one–proportion z–interval procedure to find the required confidence interval.
62)
A researcher wishes to estimate the proportion of adults in the city of Darby who are vegetarian. In
a random sample of 1354 adults from this city, the proportion that are vegetarian is 0.049. Find a
99% confidence interval for the proportion of all adults in the city of Darby that are vegetarians.
62)
A)
0.0396 to 0.0584
B)
0.0339 to 0.0641
C)
0.0140 to 0.0840
D)
0.0431 to 0.0549
Assume that you wish to estimate a population proportion, p. For the given margin of error and confidence level,
determine the sample size required.
63)
A political action committee is interested in finding out what proportion of voters will support an
environmental initiative. Obtain a sample size that will ensure a margin of error of at most 0.07 for
a 95% confidence interval. Similar initiatives in the past have gotten 93% support.
63)
A)
4
B)
52
C)
46
D)
156
^
Find the required sample size without making a guess for the observed value of p.
64)
A manufacturer wishes to estimate the proportion of washing machines leaving the factory that are
defective. Obtain a sample size that will ensure a margin of error of at most 0.017 for a 92%
confidence interval.
64)
A)
25
B)
2649
C)
26
D)
2650
Assume that you wish to estimate a population proportion, p. For the given margin of error and confidence level,
determine the sample size required.
65)
You wish to estimate the proportion of all voters in California who plan to vote in favor of a certain
ballot measure. Obtain a sample size that will ensure a margin of error of at most 0.025 for a 95%
confidence interval. Assume that it is reasonable to presume that of the voters sampled, the
proportion in favor of the measure will be between 0.66 and 0.79.
65)
A)
972
B)
1537
C)
1380
D)
1020
66)
A university’s administrator wishes to estimate the proportion of graduates who have not found
employment in their major field one year after graduation. Obtain a sample size that will ensure a
margin of error of at most 0.05 for a 99% confidence interval. It is deemed reasonable to presume
that of those sampled, the proportion who have not found employment will be at most 0.11.
66)
A)
150
B)
13
C)
260
D)
312
Use the one–proportion z–interval procedure to find the required confidence interval.
67)
Of 129 adults selected randomly from one town, 31 of them smoke. Construct a 99% confidence
interval for the percentage of all adults in the town that smoke.
67)
A)
17.8% to 30.2%
B)
16.7% to 31.4%
C)
15.3% to 32.8%
D)
14.3% to 33.7%