1. Merrill Lynch Securities and Health Care Retirement Inc. are two large employers in down-town Toledo, Ohio. They are considering jointly offering child care for their employees. As a part of the feasibility study, they wish to estimate the mean weekly child-care cost of their employees. A sample of 10 employees who use child care reveals the following amounts spent last week.
|
$107 |
$92 |
$97 |
$95 |
$105 |
$101 |
$91 |
$99 |
$95 |
$104 |
Develop a 90% confidence interval for the population mean. Interpret the result.
2. The Greater Pittsburgh Area Chamber of Commerce wants to estimate the mean time workers who are employed in the downtown area spend getting to work. A sample of 15 workers reveals the following number of minutes spent traveling.
|
29 |
38 |
38 |
33 |
38 |
21 |
45 |
34 |
|
40 |
37 |
37 |
42 |
30 |
29 |
35 |
Develop a 98% confidence interval for the population mean. Interpret the result.
3. Duncan Jones kept careful records of the fuel efficiency of his car. After the first 100 times he filled up the tank, he found the mean was 23.4 miles per gallon (mpg) with a population standard deviation of 0.9 mpg.
(a) Compute the 95 percent confidence interval for his mpg
(b) True or False: The population mean (?) is a random variable that will fall within a confidence interval with 95% probability (with repeated sampling). State an explanation for your answer
