10.15 [PT10-15] The weights of eight people before they stopped smoking and 5 weeks after they stopped smoking are as follows:

1 2 3 4 5 6 7 8 Before 148 176 153 116 129 128 120 132 After 154 179 151 121 130 136 125 128 At the 0.05 level of significance, does this sample present enough evidence to justify the conclusion that weight increases if one quits smoking? Assume normality.