In order to find out the effect of certain oral contraceptive on weight change, nine healthy females were weighed prior to start of the medication, and again at the end of a 3--month period. (See the weights below.) The sample SD of difference scores is 4.33. Conduct a hypothesis test using 5% significance level to test the claim that females experience weight change following three months of oral contraceptive use. (We can suppose that the difference scores are normally distributed.)
Subject Initial weight (lbs) End weight (lbs)
1 120 123
2 141 143
3 130 140
4 150 145
5 135 140
6 140 143
7 120 117
8 140 141
9 135 137