A box contains 35 blue, 25 white and 40 red marbles. If a marble is drawn at random from the box, find the probability that the drawn marble is (i) white (ii) not blue (iii) neither white nor blue.

Given:

Number of blue marbles = 35

Number of white marbles = 25

Number of red marbles = 40

Total number of marbles in the sample = 35 + 25 + 40 = 100

(i). Probability of getting a white marble =

Thus, probability of getting a blue card is 1/4.

(ii). Probability that the card drawn will not be a blue marble = 1 – Probability of getting a blue marble …(i)

So, probability of getting a blue marble =

Substituting this value in equation (i), we get

Probability that the draw will not be of a blue marble =

Thus, probability that it will be not a blue marble = 13/20.

(iii). Probability that it will be neither white nor blue marble = Probability of getting red marble …(i)

Probability of getting red marble =

Thus, probability that it will be neither white nor blue marble = 2/5.