29) Researchers have estimated that office workers in Germany receive an average of 15.0 fax messages per day. Assuming this finding to be based on a simple random sample of 80 German office workers, with a sample standard deviation of sx = 3.5 messages, the constructed 95% confidence interval for the true population mean is:
29b. Would it be unusual if another sample of this size were to have a mean of 16.5 faxes?
a)
| sample mean 'x̄= | 15.00 |
| sample size n= | 80.00 |
| sample std deviation s= | 3.500 |
| for 95% CI; and 79 df, value of t= | 1.990 | |
| margin of error E=t*std error = | 0.78 | |
| lower bound=sample mean-E = | 14.22 | |
| Upper bound=sample mean+E = | 15.78 | |
| from above 95% confidence interval for population mean =(14.22 , 15.78 ) | ||
b)
since 16.5 falls outside the 95% confidence interval, this appears to be unusual.
29) Researchers have estimated that office workers in Germany receive an average of 15.0 fax messages...
Researchers have studied the role that the age or workers has in determining the hours per month spent on personal tasks. A sample of 1,686 adults were observed for one month. The data are: Age Group 18-24 25-44 45-64 Mean 4.17 4.04 4.31 Std Dev 0.75 0.81 0.82 N 241 768 677 Construct a 95 percent confidence interval for the mean hours spent on personal tasks for 45-64 year olds.