2)The age when smokers first start from previous studies is
normally distributed with a mean of 13 years old with a population standard
deviation of 1.3 years old. A survey of smokers of this generation was
done to estimate if the mean age has changed. The sample of 33 smokers
found that their mean starting age was 13.2 years old. Find the 90% confidence
interval of the mean.

3)You are a researcher studying the lifespan of a certain species
of bacteria. A preliminary sample of 35 bacteria reveals a sample mean
of ¯x=76x¯=76 hours with a standard deviation of s=4.4s=4.4 hours. You would like to estimate the mean lifespan
for this species of bacteria to within a margin of error of 0.8 hours at a
95% level of confidence.

What sample size should you gather to achieve a 0.8 hour margin of
error? Round your answer up to
the nearest whole number.

n =
bacteria

4) You are interested in estimating the the
mean age of the citizens living in your community. In order to do this, you
plan on constructing a confidence interval; however, you are not sure how many
citizens should be included in the sample. If you want your sample estimate to
be within 4 years of the actual mean with a confidence level of 90%, how many
citizens should be included in your sample? Assume that the standard deviation
of the ages of all the citizens in this community is 17 years.

Sample Size:

5)
You measure 41 textbooks' weights, and find
they have a mean weight of 35 ounces. Assume the population standard deviation
is 12.2 ounces. Based on this, construct a 80% confidence interval for the true
population mean textbook weight.

Give your answers as decimals, to two places

answer- < U < answer

6) Given the interval estimate for the mean
(9.4, 19.4), the point estimate for the mean is ?

and the
margin of error is ?

7)
You measure 42 textbooks' weights, and find
they have a mean weight of 57 ounces. Assume the population standard deviation
is 4.2 ounces. Based on this, construct a 99% confidence interval for the true
population mean textbook weight. Round answers to at least 4 decimal places.

8) Given
that x̄ = 39, n = 52, and σσ = 5, then we can be 95% confident that
the true mean, μμ, lies
between the values and

9) If a school
district takes a random sample of 64 Math SAT scores and finds that the average
is 439, and knowing that the population standard deviation of Math SAT scores
is intended to be 100. Find a 90 % confidence interval for the mean math SAT
score for this district.

Give your answers as decimals, to two places:

Answer <U< answer

11) You measure 32 textbooks' weights, and find
they have a mean weight of 76 ounces. Assume the population standard deviation
is 14.9 ounces. Based on this, construct a 99% confidence interval for the true
population mean textbook weight.

Give your answers as decimals, to two places

answer. < μμ < answer in ounces

14)
If n=19, ¯xx¯(x-bar)=45,
and s=2, find the margin of error at a 95% confidence level

Give your answer to two decimal places.

15) In a survey, 7 people were asked how much they
spent on their child's last birthday gift. The results were roughly bell-shaped
with a mean of $37 and standard deviation of $4. Find the margin of error at a
90% confidence level.

Give your answer to two decimal places.

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