SOLUTION: One day 13 babies are born at a hospital. Assuming each baby has an equal chance of being a boy or a girl what is the probability that at most 11 of the 13 babies are girls

Algebra ->  Probability-and-statistics -> SOLUTION: One day 13 babies are born at a hospital. Assuming each baby has an equal chance of being a boy or a girl what is the probability that at most 11 of the 13 babies are girls      Log On


   



Question 1132191: One day 13 babies are born at a hospital. Assuming each baby has an equal chance of being a boy or a girl what is the probability that at most 11 of the 13 babies are girls
Found 2 solutions by Boreal, ikleyn:
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
What is the probability there are 12 or 13 girls?
for 12: 13C12*.5^12*.5^1 or 13/4096=0.0016
for 13: 1/4096=0.0001
Probability it is NOT those is 1-0.017 or 0.983

Answer by ikleyn(52786) About Me  (Show Source):
You can put this solution on YOUR website!
.

  The probability that at most 11 of the 13 babies are girls =


= the COMPLEMENT to the probability that all babies are girls or 12 babies are girls = 


    = 1 - 1%2F2%5E13 - C%5B13%5D%5E12%2A%281%2F2%5E12%29%2A%281%2F2%29 = 1 - 1%2F8192 - 13%2F8192 = 0.9983 = 99.83%.