Question:
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?
[A].
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?
[A].
10 |
21 |
[B].
11 |
21 |
[C].
2 |
7 |
[D].
5 |
7 |
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 ` | ||||
|
||||
= 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 | ||||
|
||||
= 10. |
P(E) = | n(E) | = | 10 | . |
n(S) | 21 |