An automobile club reported that the average price of regular gasoline in a certain state was $2.63 per gallon. The following data show the price per gallon of regular gasoline for 15 randomly selected stations in the state. Complete parts a through c below. 2.67, 2.52, 2.59, 2.74, 2.63, 2.54, 2.74, 2.72, 2.69, 2.58, 2.61, 2.54, 2.72, 2.68, 2.56

a. Construct a 95% confidence interval to estimate the average price per gallon of gasoline in the state.