A couple has six children what is the probability that they have all boys

For any birth we have only two possible outcomes either boy or girl. So the chance of getting boy or girl on birth same which is 1/2.

The probability of getting baby boy or baby girl on any birth is

P (Boy) = P (Girl) = 0.5

If a couple has six children then probability that all are boys is

P (all six are boy) = (0.5) ^6

= 0.015

The probability that all six are boy is 0.015