Suppose ? 1 and ? 2 are true mean stopping distances at 50 mph for cars of a certain type equipped with two different types of braking systems. the data follows: m = 5, x = 114.7, s1 = 5.04, n = 5, y = 129.9 and s2 = 5.37.

(a) calculate a 95% ci for the difference between true average stopping distances for cars equipped with system 1 and cars equipped with system 2.