A bag contains a black ball, a red ball and a green ball, all the balls are identical in shape and size. A ball is drawn from the bag without looking into it. What is the probability that the ball drawn is :

(i) a red ball

(ii) not a red ball

(iii) a white ball.

(i) Total number of outcomes = Total number of balls = 1 black ball + 1 red ball + 1 green ball = 3

Number of favourable outcomes (Getting a red ball) = 1

P(Getting a red ball) = $\dfrac{\text{Number of favourable outcomes}}{\text{Total number of outcomes}}$

= $\dfrac{1}{3}$

Hence, the probability of getting a red ball is $\dfrac{1}{3}$.

(ii) Total number of outcomes = Total number of balls = 1 black ball + 1 red ball + 1 green ball = 3

Number of favourable outcomes (Getting not a red ball) = 2 (black ball, green ball)

P(Getting not a red ball) = $\dfrac{\text{Number of favourable outcomes}}{\text{Total number of outcomes}}$

= $\dfrac{2}{3}$

Hence, the probability of getting not a red ball is $\dfrac{2}{3}$.

(iii) Total number of outcomes = Total number of balls = 1 black ball + 1 red ball + 1 green ball = 3

Number of favourable outcomes (Getting a white ball) = 0

P(Getting a white ball) = $\dfrac{\text{Number of favourable outcomes}}{\text{Total number of outcomes}}$

= $\dfrac{0}{3}$

= 0

Hence, the probability of getting a white ball is 0.