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

Options

A. `(3)/(5)`
B. `(2)/(5)`
C. `(5)/(36)`
D. `(1)/(36)`

Answer

B

Explanation

Consider the following events :
A=Number 4 appears at least once,
B=The sum of the numbers appearing is 6.
`therefore` Required probaility
`=P(A//B)`
= Probability of occurrence of A when B is taken as the sample space
Number of elementary events favourable to
`=("A which are favourable to B")/("Number of elementary events favourable to B")=(2)/(5)`