kukki and fukki are a married couple (dont ask me who he is and who she is) :)

They have two kids, one of them is a girl. Assume safely that the probability of each gender is 1/2.

What is the probability that the other kid is also a girl?

Hint: It is not 1/2 as you would first think.

1/3

This is a famous question in understanding conditional probability, which simply means that given some information you might be able to get a better estimate.

The following are possible combinations of two children that form a sample space in any earthly family:

Girl - Girl

Boy - Girl

Boy - Boy

Since we know one of the children is a girl, we will drop the Boy-Boy possibility from the sample space.

This leaves only three possibilities, one of which is two girls. Hence the probability is 1/3