6. A restaurant tried to increase business on Monday night, by featuring a special $1.00 dessert menu. The number of diners on each of 11 Mondays recorded while the special menu was in effect. The data were

119 139 121 126 128 108 63 118 109 131 142

a. Find a 95% confidence interval the long-run number of diners.

b. Before the special menu, the restaurant average 105.2 diners per Monday night. Is it t reasonable to interpret the confidence interval from part "a" as indicating that the special menu did not increase the average number of diners?