(iv) There are 3 red, 3 white and 3 green balls in a bag. One ball is drawn at random from a bag :
P is the event that ball is red.
Q is the event that ball is not green.
R is the event that ball is red or white.
Sol. Let 3 red balls, 3 white balls and 3 green balls be denoted as R1, R2, R3, W1, W2, W3 and G1, G2, G3 respectively.
P is the event that the ball is red
P = { R1, R2, R3 }
∴ n (P) = 3
Q is the event that the ball is not green
Q = { R1, R2, R3, W1, W2, W3 }
∴ n (Q) = 6
R is the event that the ball is red or white
R = { R1, R2, R3, W1, W2, W3 }
∴ n (R) = 6
