A random selection of volunteers at a research institute have been exposed to a typical cold virus. After they started to have cold symptoms, 15

of them were given multivitamin tablets daily which contain 1

gram of vitamin C and various other vitamins and minerals. The remaining 15

volunteers were given tablets only containing 4

grams of vitamin C. For each individual, the length of time taken to recover from cold is recorded. At the end of the experiment the following data are obtained:

It is known that the population standard deviation of recovery time from cold is 1.8

days when treated with multivitamin, and the population standard deviation of recovery time from cold is 1.5

days when treated with vitamin C tablets. It is also known that both populations are approximately normally distributed. The researchers claim that the mean recovery time, 1

, of the patients treated with multivitamin is less than or equal to the mean recovery time 2

, of the patients who are treated with vitamin C tablets. At the 0.05

level of significance, is there enough evidence to reject this claim? Perform a one-tailed test. Then fill in the table below.