15. Drug Potency To properly treat patients, drugs prescribed by physicians must have not only a mean potency value as specified on the drug’s container, but also small variation in potency values. A drug manufacturer claims that his drug has a potency of 56 .1 milligram per cubic centimeter (mg/cc). A random sample of four containers gave potency readings equal to 4.94, 5.09, 5.03, and 4.90 mg/cc.

a. Do the data present sufficient evidence to indicate that the mean potency differs from 5 mg/cc?

b. Do the data present sufficient evidence to indicate that the variation in potency differs from the error limits specified by the manufacturer? (hint: It is sometimes difficult to determine exactly what is meant by limits on potency as specified by a manufacturer.
Since he implies that the potency values will fall into the interval 56.1 mg/cc with very high probability—the implication is almost always—let us assume that the range .2 or 4.9 to 5.1 represents 6 , as suggested by the Empirical Rule.)