Question

a) An epidemiologist with the Florida Deparment of Health needs
to esimate the proportion of Floridians who are infected with the
corona virus but are asymptomatic (show no signs of the virus). The
epidemiologist compiled a preliminary random sample of infected
patients and found that 39% of the sample were also
asymptomatic.

How large a sample should be selected such that the margin of error
of the estimate for a 96% confidence interval is at most 1.96%.
Round the solution *up* to the nearest whole number.

n=

b)COVID-19 (novel corona virus) took the world by surprise in
late 2019. By early 2020, nearly all countries worldwide were
affected.

Early reports have claimed that a large percentage of those
infected with the corona virus were asymptomatic (showed no
symptoms of the virus). The rate of asymptomatic infections is
important, since such people can unwittingly spread the virus to
those around them.

Suppose the U.S. Centers for Disease Control and Prevention (CDC)
needs to estimate the proportion of the infected population that is
also asymptomatic. A random sample of 1155 infected patients is
examined and 197 are observed to be asymptomatic.

Determine the point estimate, ˆp and the sample standard deviation,
sˆp. Round the sample proportion to four decimal places and round
the standard deviation to six decimal places, if necessary.

ˆp=

sˆp=

Using a 99% confidence level, determine the margin of error, E, and
a confidence interval for the proportion of *all* patients
who are infected with the corona virus and are also asymptomatic.
Report the confidence interval using interval notation. Round
solutions to four decimal places, if necessary.

The margin of error is given by E=.

A 99% confidence interval is given by _____

c)

The St. Lucie County Economic Development Board needs to
estimate the proportion of all county residents who have earned at
least a bachelor's degree. A random sample conducted by the St.
Lucie County Economic Development Board found that 19% of all
county residents held at least a bachelor's degree.

Find three different confidence intervals - one with sample size
380, one with sample size 589, and one with sample size 756. Assume
that 19% of the county residents in each sample have earned at
least a bachelor's degree. Notice how the sample size affects the
margin of error and the width of the interval.

Report confidence interval solutions using interval notation.
Report all solutions in *percent* form, rounded to two
decimal places, if necessary.

- When n=380, the margin of error for a 95% confidence interval
is given by .

When n=380, a 95% confidence interval is given by . - When n=589, the margin of error for a 95% confidence interval
is given by .

When n=589, a 95% confidence interval is given by . - When n=756, the margin of error for a 95% confidence interval
is given by .

When n=756, a 95% confidence interval is given by .

Answer #1

Suppose a government official in Phoenix, Arizona, wants to know what proportion of Phoenix residents are infected with the COVID-19 virus. Because of the limited availability of tests, she cannot test all the residents of Phoenix. A random sample of 180 Phoenix residents was taken, and these residents were tested for the virus. Of these 180 people, 36 were found to be infected with the virus. Find a 95% confidence interval for the true proportion of Phoenix residents who are...

Assume that a sample is used to estimate a population proportion
p. Find the margin of error E that corresponds to the given
statistics and confidence level. Round the margin error to four
decimals
95% confidence; n=380, x=50

1. Public health researchers in want to estimate the proportion
of residents classified as obese in the county. In a study of 400
residents of the county, 129 were classified as obese. What is the
margin of error for a 99% confidence interval for p, the true
proportion of residents that are obese according to this
classification. Give you answer to 3 decimal places.
2. In a sample of 110 US residents, 46 said that they had approved
of the...

Find the margin of error for the 95% confidence interval used to
estimate the population proportion.
12) In clinical test with 2349 subjects. 1232 showed
improvement from the treatment
Use the given degree of confidence and sample data to
construct a confidence interval for the population proportion
p
13) n=101,x=73;88 percent

An epidemiologist is worried about the prevalence of the flu in
East Vancouver and the potential shortage of vaccines for the area.
She will need to provide a recommendation for how to allocate the
vaccines appropriately across the city. She takes a simple random
sample of 334 people living in East Vancouver and finds that 32
have recently had the flu. Suppose that the epidemiologist wants to
re-estimate the population proportion and wishes for her 95%
confidence interval to have...

A researcher wants to construct a 95% confidence interval for
the proportion of elementary school students in Seward County who
receive free or reduced-price school lunches. What sample size is
needed so that the confidence interval will have a margin of error
of 0.03?

(1 point) An epidemiologist is worried about the prevalence of
the flu in East Vancouver and the potential shortage of vaccines
for the area. She will need to provide a recommendation for how to
allocate the vaccines appropriately across the city. She takes a
simple random sample of 331 people living in East Vancouver and
finds that 36 have recently had the flu.
Suppose that the epidemiologist wants to re-estimate the
population proportion and wishes for her 95% confidence interval...

QUESTION PART A: Assume that a sample is used to estimate a
population proportion p. Find the margin of error
M.E.that corresponds to a sample of size 300 with 44%
successes at a confidence level of 99.9%.
M.E. = %
Answer should be obtained without any preliminary rounding.
However, the critical value may be rounded to 3 decimal places.
Round final answer to one decimal place
QUESTION PART B: We wish to estimate what percent of adult
residents in a...

An epidemiologist is worried about the prevalence of the flu in
East Vancouver and the potential shortage of vaccines for the area.
She will need to provide a recommendation for how to allocate the
vaccines appropriately across the city. She takes a simple random
sample of 338 people living in East Vancouver and finds that 35
have recently had the flu. Suppose that the epidemiologist wants to
re-estimate the population proportion and wishes for her 95%
confidence interval to have...

How's the economy? A pollster wants to construct a 95 %
confidence interval for the proportion of adults who believe that
economic conditions are getting better.
(a) A poll taken in July 2010 estimates this proportion to be
0.41 . Using this estimate, what sample size is needed so that the
confidence interval will have a margin of error of 0.02 ?
(b) Estimate the sample size needed if no estimate of p is
available. Part 1 of 2
(a)...

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