404 CHAPTER 6 Inferential Statistics
- Suppose that a coin is tossed 320 times, with the total number of
“heads” being 140. At the 5% level, should the null hypothesis
that the coin is fair be rejected? - A candidate claims that he has the support of at least 54% of the
voting public. A random survey of 1000 voters reveals that among
those sampled, this candidate only had the support of 51%. How
would you report these results? - Ten healthy subjects had their diastolic blood pressures measured
before and after a certain treatment. Evaluate the null hypothesis
that there was no change against the alternative that the blood
pressure was lowered as a result of the treatment. Use a 95%
significance level.
Systolic Blood Pressure
Before Treatment 83 89 86 91 84 91 88 90 86 90
After Treatment 77 83 85 92 85 86 91 88 88 83- A growing number of employers are trying to hold down the costs
that they pay for medical insurance for their employees. As part of
this effort, many medical insurance companies are now requiring
clients to use generic-brand medicines when filling prescriptions.
An independent consumer advocacy group wanted to determine
if there was a difference, in milligrams, in the amount of active
ingredient between a certain “name” brand drug and its generic
counterpart. Pharmacies may store drugs under different condi-
tions. Therefore, the consumer group randomly selected ten differ-
ent pharmacies in a large city and filled two prescriptions at each
of these pharmacies, one of the “name” brand and the other for
the generic brand of the same drug. The consumer group’s labora-
tory then tested a randomly selected pill from each prescription to
determine the amount of active ingredient in the pill. The results
are given in the table below.