Probability and Statistics

Question

n a statistics class there are 18 juniors and 10 seniors; 6 of the seniors are females and 12 of the juniors are males. if a student is selected at random, find the probability of selecting the following: a) P( a junior or a female) b) P(a senior or a female) c) P(a junior or a senior)

Answer 1

a) P(a junior or a female)=P(a junior)+P(a female)-P(a junior and a female)=18/28+12/28-6/28=24/28=6/7

b) P(a senior or a female)=P(a senior)+P(a female)-P(a senior and a female)=10/28+12/28-6/28=16/28=4/7

c) P(a junior or a senior)=1, because the class is cosisted of juniors and seniors only.