Refer to the hypothesis test described in Exercise 1.

a. Is the hypothesis test left-tailed, right-tailed, or two-tailed?

b. If the requirements are satisfied, what distribution should be used for the hypothesis test: normal, Student t, chi-square, binomial?

Exercise 1

Students of the author collected a simple random sample of times (sec) of wristwatch errors, and a few of those times are listed below. Negative values correspond to watches that are running ahead of the actual time. Assuming that we want to use a 0.05 significance level to test the claim that the sample is from a population with a mean equal to 0 sec, identify the null hypothesis and the alternative hypothesis. 

140 -85 325 20 305 205 20 -93