An automotive company is considering two types of batteries for its automobile. Sample information on the life of the battery is being used. Twenty batteries of type A and twenty batteries of type B are being used. The summary statistics are XA = 32.91, x_B = 30.47, S_A = 1-57, and S_B – 1.74. Assume the data on each battery are normally distributed and assume σ_A = σ_B.

(a) Find a 95% confidence interval on μ_A – μ_B.

(b) Draw some conclusion from (a) that provides some insight into whether A or B should be adopted.