Find the probability that a family with five children does not have a boy, if the sexes

Question:

Find the probability that a family with five children does not have a boy, if the sexes of children are independent and if
a) A boy and a girl are equally likely.
b) The probability of a boy is 0.51.
c) The probability that the ith child is a boy is 0.51 − (i/100).