Two cards are drawn simultaneously from well shuffled pack of 52 cards, then mean and variance of number of red cards are : |
2, 2/25 1, 50/51 1,25/51 2, 52/102 |
1,25/51 |
The correct answer is Option (3) → 1,25/51 The expected value (mean) is, $E(x)=n×\frac{k}{N}=2×\frac{26}{52}$ $=2×\frac{1}{2}=1$ The variance, $Var(x)=n×\frac{k}{N}×\frac{N-k}{N}×\frac{N-n}{N-1}$ $=2×\frac{26}{52}×\frac{26}{52}×\frac{50}{51}$ $=\frac{25}{51}$ |