A researcher claims that all call center agents sleep for an average that is less than or equal to 7.5 hours per day with a population standard deviation of 1.4 hours per day.

Question

A researcher claims that all call center agents sleep for an average that is less than or equal to 7.5 hours per day with a population standard deviation of 1.4 hours per day. To validate the claim, she selected a random sample of 31 call center agents, who provided a mean of 7.8 hours per day. Assuming a normal distribution, what is the p-value at 1% significance level? Round your answer to four decimal places. Do not place any unit.

Answer 1

Here you would run a z-test and obtain the z-value. Then look in a statistics text for the z-table and find the z-values' corresponding percentage then subtract from 1 only if the table shows percentages for the whole bell curve. If the table shows for have the bell curve, then you need to add .5 to the percentage and then subtract it from 1.

For example, if I obtain a z-value of 1.25, one statistic table may say .8944. So 1-.8944 is .1056.

.1056 is the p-value

If the table shows percentages for half the bell curve you will see .3944. Add .5 to .3944 and you still get .8944 Then subtract from 1 as shown above.