SOLUTION: A family has 4 children. Let B be the event "the family has children of both sexes". Find P(B).

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Question 866158: A family has 4 children. Let B be the event "the family has children of both sexes". Find P(B).
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let A be the event "the family has children of only one sex".
Let B be the event "the family has children of both sexes".
It's clear that
P%28A%29%2BP%28B%29=1
There are 16 possible combinations of sexes from MMMM, MMMF, through, FFFM, FFFF.
Only two fall into the A category {MMMM,FFFF} so,
P%28A%29=2%2F16=1%2F8
So then,
P%28B%29=1-P%28A%29
P%28B%29=1-1%2F8
P%28B%29=7%2F8