Question

In a survey of 1000 US adults, twenty percent say they never exercise. This is the highest level seen in five years.

a) Verify that the sample is large enough to use the normal distribution to find a confidence interval for the proportion of Americans who never exercise. (Are the conditions met?) Use a formula to justify your answer or, if possible, explain your reasoning.

b) Construct a 90% confidence interval for the proportion of U.S. adults who never exercise. Show your work. Use three decimal places in your interval.

c) Provide an interpretation of your interval in context.

d) Given the results of the study, is it plausible that 1/3 of US adults never exercise? Explain your answer.

e) Suppose you want to estimate the proportion of local adults who never exercise with 95% confidence and a 5% margin of error. Californians tend to exercise more than Americans in other states, so we will use as a conservative estimate of the proportion of adults who never exercise. (Hint: Use p ~ .) How many people should you sample?

Answer #1

n = 1000

p = 0.20

(a) n*p = 1000*0.20 = 200 10

n*(1 - p) = 1000*(1 - 0.20) = 800 10

The sample is large enough to use the normal distribution to find a confidence interval for the proportion of Americans who never exercise.

(b) The 90% confidence interval for the proportion of U.S. adults who never exercise.

= (0.1792, 0.2208)

(c) We are 90% confident that the true proportion of U.S. adults who never exercise is between 0.1792 and 0.2208.

(d) Since 1/3 = 0.33 is not in the confidence interval, we cannot say that it is plausible that 1/3 of US adults never exercise.

(e) n = (1.96/0.05)^2*0.5*0.5 = 385

A company surveyed 1000 US adults and asked them under what
circumstances they would give personal information to a company.
Twenty nine percent said they would never give personal data to a
company.
a. Construct an 87% confidence interval for population proportion
of customers who would never give personal data to a company
b. Based on (b), can you conclude that the true proportion is
different than 16%? Explain why

In a survey of 1000 US adults, 490 opposes allowing transgender
students to use the bathroom of the opposite biological sex.
Construct a 90% confidence interval for the population proportion
of adults who oppose allowing transgender students to use the
bathroom of the opposite biological sex.

In a survey of 1000 Canadian adults, 790 say that the energy
situation in Canada is very or fairly serious. 2. Construct a 95%
confidence interval for the population proportion (a) The critical
value: (b) The margin of error: (c) The lower limit of the
interval: (d) The upper limit of the interval: 3. find the minimum
sample size needed to estimate the population proportion at the 99%
confidence level in order to ensure that the estimate is accurate
within...

In a survey of 2331 adults, 711 say they believe in UFOs.
Construct a 99 % confidence interval for the population proportion
of adults who believe in UFOs. A 99% confidence interval for the
population proportion is ( nothing, nothing). (Round to three
decimal places as needed.) Interpret your results. Choose the
correct answer below. A. With 99% probability, the population
proportion of adults who do not believe in UFOs is between the
endpoints of the given confidence interval. B....

In a survey, 376 out of 1,078 US adults said they drink at least
4 cups of coffee a day. Find a point estimate (P) for the
population proportion of US adults who drink at least 4 cups of
coffee a day, then construct a 99% confidence interval for the
proportion of adults who drink at least 4 cups of coffee a day

In a survey of 2260 adults, 708 say they believe in UFOs.
Construct a 95% confidence interval for the population proportion
of adults who believe in UFOs.
A 95% confidence interval for the population proportion is
(_,_). (Round to three decimal places as needed.) Interpret
your results.
Choose the correct answer below
. A. With 95% confidence, it can be said that the sample
proportion of adults who believe in UFOs is between the endpoints
of the given confidence interval....

3- A recent Gallup poll of a random sample of 1,015 US adults
reported that a 95% confidence interval for the population
proportion of adults who frequently worry about being the victim of
identity theft is (0.32, 0.40).
(a) We are 95% confident that what parameter is contained in
this interval? (Circle your answer.) Can we say that there is a
probability of 95% that this parameter is actually contained in
this interval?
A) sample proportion B) population proportion C)...

In a survey on supernatural experiences, 724 of 4003 adult
Americans surveyed reported that they had seen or been with a
ghost.
(a) What assumption must be made in order for it to be
appropriate to use the formula of this section to construct a
confidence interval to estimate the proportion of all adult
Americans who have seen or been with a ghost?
We need to assume that there are only 724 adult Americans.We
need to assume that the 4003...

A researcher wishes to estimate, with
ninety percent*
confidence, the population proportion of adults who say
chocolate is their favorite ice cream flavor. Her estimate must be
accurate within
twenty two percent*
of the population proportion.
Now:
(a) No preliminary estimate is available. Find the minimum
sample size needed.
(b) Find the minimum sample size needed, using a prior study
that found that
twenty percent
of the respondents said their favorite flavor of ice cream is
chocolate.
(c) Compare the...

in
a survey of 3303 adults ages 57 through 85 years, it was found that
80.2% of them used at least one prescription medication. Complete
parts 1-3 below
1: how many of the 3303 subjects used at least one
prescription medication?
2: construct a 90% confidence interval estimate of the
percentage of adults ages 57 through 85 years who use at least one
prescription medication
3: what do the results tell us about the proportion of The
adults who use...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 2 minutes ago

asked 39 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 2 hours ago

asked 3 hours ago

asked 3 hours ago

asked 3 hours ago

asked 4 hours ago

asked 4 hours ago

asked 5 hours ago