P(s) = 45/125 = 0.360 P(A&C) = 38/125 = 0.304 Probability that one is not in Arts and Crafts = 1- P(A&C) = 1-0.304 = 0.696
Therefore, Probability that the child selected is in swimming when its known they didn't sign for Arts and craft = Probability they signed for swimming * Probability that they didn't sign for Arts and Crafts = 0.360*0.696 = 0.25056
There are total 45 children who sign up for swimming, but 12 children are sign up for both, so only 33 students are only for swimming. and there 54 children who are not sign up either one. plus 33 children ( swimming), total is 87 children who did not sign up for arts and crafts
