Question

According to a study of employed U.S. adults ages 18 and over, the mean number of workdays missed due to illness or injury in the past 12 months is 3.5 days. You randomly select 25 employed U.S. adults ages 18 and over and find that the mean number of workdays missed is 4 days. Assume the population standard deviation is 1.5 days and the population is normally distributed.

Answer 1

Here, we do testing of hypothesis based on the scenario given. Here, we have to test that whether the the mean number of workdays missed due to illness or injury in the past 12 months by adults of age 18 and above is 3.5 days or not.

We consider the following hypothesis-

where, = population mean = 3.5 days.

The test statistic used-

where, = sample mean = 4 keys

   = population standard deviation = 1.5 days.

n = sample number = 25

Thus, we calculate the test statistic as-

= 1.6667

Here, we consider the 0.05 significance level. The critical value of the test is - = 1.960

Now, we reject the null if |T| >.

Here, |T|< 1.960, so we accept the null and conclude that the mean number of workdays missed due to illness or injury in the past 12 months by adults of age 18 and above is 3.5 days.