Download Name: Date: Period: ______ Chapter 23

Name: __________________________________________
Date: ______________________
Period: ______
Chapter 23-Part A: Review Problems
Find the mean and Margin of Error given the following confidence interval:
1) 72.6 < µ < 82.6
2) (207, 212)
Find the following critical values:
2) 95%; n = 120; population is normally distributed
3) 99%; n=15; population is normally distributed
4) 90%; n=12; population is skewed right.
Use the following data to conduct confidence intervals.
5) Math SAT scores for women: 95% confidence, n=15, sample mean = 496 and s=108.
6) Salaries of Statistics professors are normally distributed: 95% confidence; n=60, sample mean
= $85,678 and s = $12,345
7) The amounts of stolen and recovered merchandise from shoplifters are listed below. Conduct
a 99% confidence interval for these data.
144.95
420.00
144.00
119.96
542.88
330.96
346.95
79.99
149.99
16.96
38.00
24.99
8) A coffee machine dispenses coffee into paper cups. You’re supposed to get 10 ounces of coffee,
but the amount varies slightly from cup to cup. Here are the amounts measured in a random
sample of 20 cups. Find a 95% confidence interval based off of these sample data to capture
the true mean. Is the true mean actually captured in your interval?
Find the proper sample size.
9) If we want to estimate the mean weight of plastic discarded by households in one week, how
many households must we randomly select if we want to be 99% confident that the sample
mean is within 0.250 lb of the true population mean? If we use that sample as a pilot study, we
get a standard deviation of s=1.065 lb.
10)You have just been hired by the Boston Marketing Company to conduct a survey to estimate
the mean amount of money spent by movie patrons. The sample SD from a pilot study is $3.
Then use that estimated standard deviation to determine the sample size corresponding to
98% confidence and a $0.25 margin of error.