Question

A box contains 3 blue, 2 white, and 4 red marbles. If a marble is drawn at random from the box, what is the probability that it will be

(i) white? (ii) blue? (iii) red?

Answer 1

Saying that a marble is drawn at random is a short way of saying that all the marbles are equally likely to be drawn. Therefore, the number of possible outcomes = 3 +2 + 4 = 9

Let W denote the event ‘the marble is white’, B denote the event ‘the marble is blue’ and R denote the event ‘marble is red’.

(i) The number of outcomes favourable to the event W = 2

So, P(W)=2/9

Similarly, (ii)P(B)=3/9=1/3 and (iii) P(R)=4/9

Note that P(W) + P(B) + P(R) = 1.