Question
The average one-way commute time for a random sample of 256 area residents of a city is 90 minutes, with a standard deviation of 24 minutes.
Construct a 90% confidence interval for the mean commute time of all residents.
Construct a 98% confidence interval for the mean commute time of all residents.
Which interval is larger? Why?
Construct a 90% confidence interval for the mean commute time of all residents.
Construct a 98% confidence interval for the mean commute time of all residents.
Which interval is larger? Why?
Answers
PsyDAG
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (for two-tailed, .05 and .01) and get the respective Z scores.
90% = Mean ± Z(SD)
98% = mean ± Z(SD)
After the calculations, you should be able to answer why.
90% = Mean ± Z(SD)
98% = mean ± Z(SD)
After the calculations, you should be able to answer why.