1. Assume that IQ scores are normally distributed, with a standard deviation of 10 points and a mean of 100 points. If 130 people are chosen at random, what is the probability that the sample mean of IQ scores will not differ from the population mean by more than 2 points? (Round your answer to four decimal places.) 2. A large tank of fish from a hatchery is being delivered to a lake. The hatchery claims that the mean length of fish in the tank is 15 inches, and the standard deviation is 7 inches. A random sample of 58 fish is taken from the tank. Let x be the mean sample length of these fish. What is the probability that x is within 0.5 inch of the claimed population mean? (Round your answer to four decimal places.) 1 MATH221 Statistics 1. Find the minimum sample size n needed to estimate µ for the given values of c, s, and E. C= 0.98, s= 9.3, and E= 1 N= ______ (round to the nearest whole number) 2. You are given the sample mean and the sample standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. If convenient, use technology to construct the confidence intervals. A random sample of 40 home theater systems has a mean price of $142.00 and a standard deviation is $15.30 Construct a 90% confidence interval for the population mean. The 90% confidence interval is (______,______) (Round to two decimal places as needed) 3. You are given the sample mean and the sample standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. If convenient, use technology to construct the confidence intervals. A random sample of 38 gas grills has a mean price of $638.80 and a standard deviation of $55.30 Construct a 90% confidence interval for the population mean. The 90% confidence interval is (______,______) (Round to One decimal place as needed) 4. You are given the sample mean and the sample standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. If convenient, use technology to construct the confidence intervals. A random sample of 50 eight-ounce servings of different juice drinks has a mean of 84.4 calories and a standard deviation of 41.8 calories. The 90% confidence interval is (______,______) (Round to One decimal place as needed) 5. People were polled on how many books they read the previous year. How many subjects are needed to estimate the number of books read the previous year within one book with 90% confidence? Initial survey results indicate that ơ= 16.7 books. A 90% confidence level requires ______ subjects. (Round up to the nearest whole number as needed) 6. A doctor wants to estimate the HDL cholesterol of all 20 to 29 year old females. Ho ...

1. 1. Assume that IQ scores are normally distributed, with a
standard deviation of 10 points and a mean of 100 points. If 130
people are chosen at random, what is the probability that the
sample mean of IQ scores will not differ from the population
mean by more than 2 points? (Round your answer to four
decimal places.)
2. A large tank of fish from a hatchery is being delivered to a
lake. The hatchery claims that the mean length of fish in the
tank is 15 inches, and the standard deviation is 7 inches. A
random sample of 58 fish is taken from the tank. Let x be the
mean sample length of these fish. What is the probability that x
is within 0.5 inch of the claimed population mean? (Round your
answer to four decimal places.)
1
MATH221 Statistics
1. Find the minimum sample size n needed to estimate µ for the
given values of c, s, and E.
C= 0.98, s= 9.3, and E= 1
N= ______ (round to the nearest whole number)
2. You are given the sample mean and the sample standard
deviation. Use this information to construct the 90% and 95%
confidence intervals for the population mean. Interpret the
results and compare the widths of the confidence intervals. If
convenient, use technology to construct the confidence
intervals.
A random sample of 40 home theater systems has a mean price
of $142.00 and a standard deviation is $15.30
Construct a 90% confidence interval for the population mean.

2. The 90% confidence interval is (______,______) (Round to two
decimal places as needed)
3. You are given the sample mean and the sample standard
deviation. Use this information to construct the 90% and 95%
confidence intervals for the population mean. Interpret the
results and compare the widths of the confidence intervals. If
convenient, use technology to construct the confidence
intervals.
A random sample of 38 gas grills has a mean price of $638.80
and a standard deviation of $55.30
Construct a 90% confidence interval for the population mean.
The 90% confidence interval is (______,______) (Round to One
decimal place as needed)
4. You are given the sample mean and the sample standard
deviation. Use this information to construct the 90% and 95%
confidence intervals for the population mean. Interpret the
results and compare the widths of the confidence intervals. If
convenient, use technology to construct the confidence
intervals.
A random sample of 50 eight-ounce servings of different juice
drinks has a mean of 84.4 calories and a standard deviation of
41.8 calories.
The 90% confidence interval is (______,______) (Round to One
decimal place as needed)
5. People were polled on how many books they read the
previous year. How many subjects are needed to estimate the
number of books read the previous year within one book with
90% confidence? Initial survey results indicate that ơ= 16.7
books.

3. A 90% confidence level requires ______ subjects. (Round up to
the nearest whole number as needed)
6. A doctor wants to estimate the HDL cholesterol of all 20 to
29 year old females. How many subjects are needed to estimate
the HDL cholesterol within 3 points with 99% confidence
assuming ơ= 18.8? Suppose the doctor would be content with
95% confidence. How does the decrease in confidence affect the
sample size required?
A 99% confidence level requires ______ subjects. (Round up to
the nearest whole number as needed)
7. Construct the indicated confidence interval for the population
mean µ using (a) a t-distribution.
(a) The 90% confidence interval using a t-distribution is
(______,______) (Round to one decimal place as needed)
(b) If you had incorrectly used a normal distribution, which
interval would be wider?
8. In the following situation, assume the random variable is
normally distributed and use a normal distribution or a t-
distribution to construct a 90% confidence interval for the
population mean. If convenient, use technology to construct the
confidence interval.
(a) In a random sample of 10 adults from a nearby county, the
mean waste generated per person per day was 4.29 pounds and
the standard deviation was 1.08 pounds.
For the sample of 10 adults, the 90% confidence interval is
(______,______) (Round to two decimal places as needed)
(b) Repeat part (a), assuming the same statistics came from
sample size 400. Compare the results.
___________________________

4. 9. In a survey of 648 males ages 18-64, 394 say they have gone
to the dentist in the past year.
Construct 90% and 95% confidence intervals for the population
proportion. Interpret the results and compare the widths of the
confidence intervals. If convenient, use the technology to
construct the confidence intervals.
The 90% confidence interval for the population proportion is
(______,______) (Round to three decimal places as needed)
10. In a survey of 8000 women, 5431 say they change their nail
polish once a week. Construct a 90% confidence interval for the
population proportion of women who change their nail polish
once a week.
A 90% confidence interval for the population proportion is
(_______,_______) (Round to three decimal places as needed)