Two balls are drawn from a bag containing 3 green 4 red

Since the first ball is not replaced before the second draw, the random experiments of drawing balls are not independent.

Let Wi, Ri, Gi and Bi be the events of drawing a white ball, a red ball, a green ball and a black ball in the ith draw resp. where i = 1, 2.

Therefore, required probability

= P(balls are of diff colors)

= 1 – P(balls are of same colors)

= 1 – P(W1W2 or R1R2 or G1 G2 or B1 B2)

= 1 – [P(W1W2) + P(R1 R2) + P(G1G2) + P(B1B2)]

= 1 – [

= 1 – [

= 1 – 0.098901

= 0.901099