An experiment was planned to compare the mean time (in days) required to recover from a common cold for persons given a daily dose of 4 milligrams (mg) of vitamin C versus those who were not given a vitamin supplement. Suppose that 35 adults were randomly selected for each treatment category and that the mean recovery times and standard deviations for the two groups were as follows:

No Vitamin supplement 4 mg Vitamin C

Sample size 35 35

Sample mean 6.9 5.8

Sample standard deviation 2.9 1.2

Suppose your research objective is to show that the use of vitamin C reduces the mean time required to recover from a common cold and its complications. Give the null and alternative hypotheses for the test. Is this a one or two tailed test ?

Conduct the statistical test of the null hypothesis in part a and state your conclusion. Test using alpha = 0.05.?