The effectiveness of a new bug repellent is tested on 20 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=12 the new repellent is considered effective if it provides a percent repellency of at least 91. using α=0.05, construct a hypothesis test with null hypothesis μ=91 and alternate hypothesis μ> 91 to determine whether the mean repellency of the new bug repellent is greater than 91 by computing the following:
(a) the degrees of freedom.
(b) the test statistic.