A die is thrown twice and the sum of numbers appearing is observed to be 6. The probability that number 4 has appeared at least once is :

$\frac{2}{5}$

The correct answer is Option (1) → $\frac{2}{5}$

sum of numbers → 6

so sample space of pairs = $(1, 5), (5,1), (2,4), (4,2), (3,3)$

So probability of getting 4 at least once = $\frac{2}{5}$