A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?

Answer: Option A

Explanation:

Total number of balls = (2 + 3 + 2) = 7.

Let S be the sample space.

Then, n(S)

= Number of ways of drawing 2 balls out of 7

= ⁷C₂ `

=	(7 x 6)
	(2 x 1)

= 21.

Let E = Event of drawing 2 balls, none of which is blue.

n(E)

= Number of ways of drawing 2 balls out of (2 + 3) balls.

= ⁵C₂

=	(5 x 4)
	(2 x 1)

= 10.

P(E) =	n(E)	=	10	.
	n(S)		21