There is some variability in amount of phenobarbital in each capsule sold by manufacturer. But, the manufacturer claims that the mean value is 20.0 milligrams. To test this, a sample of 25 pills yielded sample mean of 19.7 with sample standard deviation of 1.3. What inference would you draw from these data? In particular, are the data strong enough evidence to discredit the claim of the manufacturer? Use the 5 percent level of significance.