In an attempt to increase business on Monday nights, a restaurant offers free dessert with every dinner order. Before the offer, the mean number of dinner customers on Monday nights was 152. The following are the numbers of diners on a random sample of 12 Monday nights while the offer was in effect. 206 169 191 152 212 139 142 151 174 220 192 153

Dot plot. xlsx

Part (a) - 2 Points

Look at the above dot-plot of the data. Why does the plot suggest that it is okay to conduct a hypothesis test?

Part (b)

Test at the α = 0.05 level whether or not the dessert promotion increased the mean number of dinner customers on Monday nights.