An urn contains 40 marbles; 25 are red, 10 are white, and 5 are blue. You choose one marble at random.

Question

a. What is the probability of choosing a white marble?

b. What is the probability of choosing a marble that is not blue?

c. You choose a marble at random and are told that it is not blue.

    What is the probability that it is white?

d. You choose a marble at random and are told that it is not blue.

    What is the probability that it is red?

Answer 1

P(W) = 10/40 = 1/4 = 25%

P(~B) = 35/40 = 7/8 = 87.5%

P(W/~B) = 10/35 = 2/7 = about 28.57%

P(R/~B) = 25/35 = 5/7 = about 71.43%