NeerajPathak51
This is very difficult
If the dices were not biased, the question wouldn’t have been that difficult.
The part that makes this question tricky is the fact that the dices are biased. But, if we can navigate that part, the question is a cake walk.
So, before we dive deep into the solution we must take a note of an important aspect. Had the dice not been biased the probability of each number would have been 1/6 - We all know this !
But because the dice is biased the probability if odd number appearing is three times that of an even number. We have three odd and three even numbers on the face of a dice.
If the probability of an even, P(e), number is x, the probability of an odd number, P(o), is 3x. As there are three even numbers and three odd numbers,
3(P(e)) + 3(P(o)) = 1
3(x) + 3(3x) = 1
12x = 1
x = 1/12
P(e) = 1/12
P(o) = 3/12
Once, we have got this we can apply the regular concept to solve the question.