Question

3. Class rank. Choose a college student at random and ask his or her class rank in high school. Probabilities for the outcomes are as follows: Lowest 10% Rank: Probability: Top 20% 0.40 Second 20% 0.30 Third 20% 0.20 (a) What must be the probability that a randomly chosen student was in the bottom 40% of his or her high school class?

Answer 1

lour 2 - 1. Rank Top 20% second. 20% Third 20% probabints au 0.3 0.2 - Sum of all probabilites al Pllowest hool) 1-0 4-0-3-0.g = -0.9 - soutai pl that randorily chosen Shrutent - bottom 40% of his/her - pl bottom 40%) was in school class) - digns - oto 9 total lo Top 20% second 20% Third got towest no% y - - loxo-le 10x0.3 10x0.2 108ol au :3 = 2 l 0-3 represent second 20% 9 represents top 20% ; 7-8 represent lowest hool 4-6 represent. third 2007

8 randomly students x - number are of students n bottom chose 40% - Paolo n=8 pl no more than 3) =P ( X =3) plx=x) = n pa legne Pfx53) = f (0.<1-0.01660 &c, (0.1) (093* + 18 (6.Dco. 9jo +86 (a. 1) lagg - 0.43047 +0.38864 to 1488 t R 0.63307 = 0.99498 P(x53) =8995