∴ The probability that the first ball is even numbered = | 10 |
21 |
Since the ball is not replaced there are now 20 balls left, of which 9 are even numbered.
∴ The probability that the second ball is even numbered = | 9 |
20 |
∴ Required probability = | 10 | × | 9 | = | 9 | = | 3 |
21 | 20 | 42 | 14 |
1 | × | 1 | × | 16 | = | 2 |
2 | 2 | 50 | 25 |
∴ The required probability = | 1 |
4 |