Question 4 20 points The diameter of steel rods manufactured on two different extrusion machines is being investigated. Two random samples of sizes 11 = 30 and n2 = 32 are selected. The sample summary statistics are *1 = 8.73 cm, 5 = 0.35 cm12, 52 = 8.68 cm, 55 = 0.40 cm2 . Assume that the variances of the diameters on both machines are the same. (a)Is there evidence to support the claim that the two machines produce rods with different mean diameters? Use a p-value in arriving at your conclusion. (b) Construct a 98% confidence interval for the difference