The effectiveness of a new bug repellent is tested on 14 subjects for a 10 hour period. (Assume normally distributed population.) Based on the number and location of the bug bites, the percentage of surface area exposed protected from bites was calculated for each of the subjects. The results were as follows:
x??=93, s=9
The new repellent is considered effective if it provides a percent repellency of at least 91. Using ?=0.01, construct a hypothesis test with null hypothesis ?=91 and alternative hypothesis ?>91 to determine whether the mean repellency of the new bug repellent is greater than 91 by computing the following:
(a) the degree of freedom_____.
(b) the critical t value_____.
(c) the test statistics______.
The final conclusion is
A. There is not sufficient evidence to reject the null hypothesis that ?=91. Our results do not provide enough evidence that the new bug repellent is effective.
B. We can reject the null hypothesis that ?=91. Our results indicate that the new bug repellent is effective.