Question

In a simple random sample of 90 cellphone owners, 67 own a smartphone.

- Find the 85% confidence level for the percentage of all cellphone owners who own a smartphone, based on the sample data above. Give your answers as percentages to at least two decimal places. Do not type the percent signs.

% <p<%

b. The margin of error for this confidence interval is % (give your answer as a percentage to at least two decimal places).

A major credit card company wants to estimate the percentage of its cardholders have chosen the Personal Identification Number (PIN) of 1234 [which is a very bad idea, since it’s easy for someone to guess if your card is lost or stolen]. Specifically, the company will construct a 80% confidence interval for the true percentage of its cardholders who use this PIN, using a Simple Random Sample.

What is the critical value for such a confidence interval? Give
your answer to exactly four decimal places.

Euniqua is considering running for political office, and wants to determine a 96% confidence interval for the true percentage of likely voters who will support her in the upcoming election. Assume she is able to use a Simple Random Sample from the population of likely voters.

What is the critical value for such a confidence interval? Give
your answer to exactly four decimal places.

Answer #1

(a)

**Answer: (67.82%, 81.06%)**

(b)

The margin of error is 6.62%

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Critical value for 80% confidence interval:

--------------------------------------------------------

Critical value for 96% confidence interval:

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In a simple random sample of 1180 U.S. adults from a large
population, it is found that 816 “regularly” spend more than 40
minutes per day checking email. Use this sample to estimate the
true percentage, p, of all U.S. adults in this population who
“regularly” spend more than 40 minutes per day checking email.In
each question below, give answers as percents, rounded to at least
two decimal places.
(a) Find a 95% confidence interval for p
% < p...

A simple random sample of 90 items from a population with ? = 7
resulted in a sample mean of 31. If required, round your answers to
two decimal places.
a. Provide a 90% confidence interval for the
population mean.
______ to ______
b. Provide a 95% confidence interval for the
population mean.
_____ to _____
c. Provide a 99% confidence interval for the
population mean.
_____ to _____

Smartphones: A poll agency reports that 32% of teenagers aged
12-17 own smartphones. A random sample of 100 teenagers is drawn.
Round your answers to at least four decimal places as needed. (d)
Find the probability that the proportion of the sampled teenagers
who own a smartphone is between 0.29 and 0.35. The probability that
the proportion of the sampled teenagers who own a smartphone is
between 0.29 and 0.35 is?

In a simple random sample of 460 young people, 85% had earned
a high school diploma. Complete the following parts (Round all
answers to 2 decimal places.)
a) What is the standard error for this estimate of the
percentage of all young people who earned a high school diploma?
(as a percentage). Answer: %
b) Find the margin of error, using a 95% confidence level, for
estimating the percentage of all young people who earned a high
school diploma. (as...

A certain article indicates that in a sample of 1,000 dog
owners, 610 said that they take more pictures of their dog than of
their significant others or friends, and 470 said that they are
more likely to complain to their dog than to a friend. Suppose that
it is reasonable to consider this sample as representative of the
population of dog owners.
Construct a 90% confidence interval for the proportion of dog
owners who take more pictures of their...

A certain article indicates that in a sample of 1,000 dog
owners, 680 said that they take more pictures of their dog than of
their significant others or friends, and 490 said that they are
more likely to complain to their dog than to a friend. Suppose that
it is reasonable to consider this sample as representative of the
population of dog owners.
(a)
Construct a 90% confidence interval for the proportion of dog
owners who take more pictures of...

In a simple random sample of size 63, taken from a population,
24 of the individuals met a specified criteria.
a) What is the margin of error for a 90% confidence interval for
p, the population proportion?
Round your response to at least 3 decimal places.
b) What is the margin of error for a 95% confidence interval for
p?
Round your response to at least 3 decimal places.

You are to determine the size for a simple random sample based
upon the following considerations. You are assigned the task of
determining the average age of owners of Lincoln automobiles. The
estimate for the standard deviation is 12. You are willing to
accept a maximum error of +- 2 years of age. Furthermore, the level
of confidence associated with your statistic should be 95%. Based
on these criteria, what is the size of the sample you need to
use?...

Simple random sampling was used to obtain a sample of
n = 90
elements from a population of
N = 600.
The sample mean was
x = 85,
and the sample standard deviation was found to be
s = 9.
(a)
Estimate the population total.
=
(b)
Estimate the standard error of the population total. (Round your
answer to four decimal places.)
s
=
(c)
Develop an approximate 95% confidence interval for the
population total. (Round your answers to four...

A random sample of 1800 car owners in a particular city found
324 car owners who received a speeding ticket this year. Find a 95%
confidence interval for the true percent of car owners in this city
who received a speeding ticket this year. Express your results to
the nearest hundredth of a percent.
Answer:
to %

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