M8 Problem Set

Solution. When we look back at table 6.1, we see that 96% confidence corresponds to z=2.05. If we say that the East Side Plant corresponds to population 1 and the West Side Plant corresponds to population 2, then: n4{=54, n,=41, s1=1.3, s,=1.8, x% = 5.3, Xxd = 6.8, a) We will use eqn. 8.1: L 51 8550 o s T x—x)—z’—+—+< —h <(X—%)+z | —+ — (x; —x; n ", W —Hy < (¥ —X;) n n, 132 182 132 182 +— <y —p; <(53-68)+ 2.05 |— + O —08) 203 feep Sy et A -2181 < J; — |, <—.8192 b) Notice that the entire 96% confidence interval is negative (it is never positive or zero). Therefore, we can say that we are 96% confident that there is a difference in the two population means. c) Since the entire confidence interval is negative, we can be 96% confident that (u1 - y2) is negative. This means that on average, people from the West Side Plant will be absent more days than people from the East Side Plant. Question 2 0/0pts Seven students take a speed reading course in order to improve their reading ability. The reading scores of the seven before and after taking the course are given below: Person 1 2 3 4 5 6 7 x Test Score (Before) 350 371 360 400 450 389 410 y Test Score (After) 370 366 365 413 440 420 419 Note that n = 7. We will define dq = x4 - y4. After doing the appropriate calculations, we find that .