203. The probability of a new born baby is a boy is 50% and that of a new born baby is a girl is 50%. Ten mothers are going to give birth to ten babies this morning. What is the probability that at least two babies are boys?
Probability of at least 2 babies born a boy is 1 - (probability only 0 or 1 is a boy).
Probability that there are no boys = (1/2)^10
Probability that there is just 1 boy = 10 *(1/2)^10 this is because there any one of the 10 mothers can have the boy while the others all have girls.
(1/2)^10 + 10 *(1/2)^10 = 11/(2^10)
Answer is 1 - 11/(2^10)
