A manufacturer of electronic games is considering their installation in campus bars. In a pilot study of the potential profitability of this enterprise, games were placed for one week in ten randomly chosen college bars. Denoting by x, weekly profits in dollars, the follow- ing sample results were found: x-1.120 (x-x)'-5,184

(a) Stating any assumptions you need to make, find an 80% confidence interval for mean weekly profits for all campus bars.

(b) Without doing the calculations, state whether a 90% confidence interval for the popu- lation mean would be wider than, narrower than, or the same as that found in part (a).