A newly married couple decides to continue having children until they have one of each sex. If the events of having a boy and a girl are independent and equiprobable, how many children should this couple expect?
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A newly married couple decides to continue having children until they have one of each sex. If the events of having a boy and a girl are independent and equiprobable, how many children should this couple expect?
Two, one of each ;)
Three.
The probability for exactly two children is 1/2 (i.e, the chance of the sex of child 2 being different from child 1). The probability of 3 children is (1/2)^2; the probabiliy of four is (1/2)^3 etc. So the expected value is:
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