1. How do retail stores rate? Companies such as GAP, Nordstrom, Dillard's, JC Penney, and Office Depot stated annual profits per employee with a mean of 5.1 and a standard deviation of 3.8 for a sample of 35 employees. a. Find an 80% confidence interval for the average annual profit per employee. b. Find a 90% confidence interval for the average annual profit per employee.

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1. How do retail stores rate? Companies such as GAP, Nordstrom, Dillard's, JC Penney,
and Office Depot stated annual profits per employee with a mean of 5.1 and a standard
deviation of 3.8 for a sample of 35 employees.
a. Find an 80% confidence interval for the average annual profit per employee.
b. Find a 90% confidence interval for the average annual profit per employee.
2. You are thinking about buying a motel located on Interstate 64. Before you make up
your mind, you want to estimate the average number of vehicles that go by the motel
each day in the summer. Fortunately, the highway department has been counting
vehicles on 1-64 near the motel. A random sample of 36 summer days shows an average
of 16000 cars per day with a standard deviation of 2400 cars. Find a 90% confidence
interval for the mean number of cars per summer day going past the motel.
3. A sociologist is studying marriage customs in a rural community in Denmark. A
random sample of 35 women who have been married was used to determine the age of
the woman at the time of her first marriage. The sample standard deviation was 2.3
years. How many women should be included in the sample to be 95% confident that the
sample mean of ages is within .25 year of the population mean?
8
5
e
b n
Transcribed Image Text:1. How do retail stores rate? Companies such as GAP, Nordstrom, Dillard's, JC Penney, and Office Depot stated annual profits per employee with a mean of 5.1 and a standard deviation of 3.8 for a sample of 35 employees. a. Find an 80% confidence interval for the average annual profit per employee. b. Find a 90% confidence interval for the average annual profit per employee. 2. You are thinking about buying a motel located on Interstate 64. Before you make up your mind, you want to estimate the average number of vehicles that go by the motel each day in the summer. Fortunately, the highway department has been counting vehicles on 1-64 near the motel. A random sample of 36 summer days shows an average of 16000 cars per day with a standard deviation of 2400 cars. Find a 90% confidence interval for the mean number of cars per summer day going past the motel. 3. A sociologist is studying marriage customs in a rural community in Denmark. A random sample of 35 women who have been married was used to determine the age of the woman at the time of her first marriage. The sample standard deviation was 2.3 years. How many women should be included in the sample to be 95% confident that the sample mean of ages is within .25 year of the population mean? 8 5 e b n
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