A die is thrown two times. It is found that the sum of the appeared numbers is 6. Find the conditional that the number 4 appeared at least one time.
The probability distribution of the random variable X is given by
| X | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| P(X) | 0.2 | k | 2k | 2k |
Find the variance of the random variable \(X\).