I agree... the selection process has no memory. It doesn't remember the sex of the first element when choosing the second. This is like throwing a coin. Each throw is independent, since the coin has no memory. It is not like opening two doors where behind one is a prize. In that case after opening the first one, the second one will hold the prize because there's "memory" involved.Dr Herbie said:It's 50%.
The sex of the second child is not affected at all by the sex of the first child; knowing that one of the children is a girl is irrelevant in detemining the sex of the other.
Trust me, I'm a Doctor (of biology)
You could easily transform this given problem into the coin scenario. But you can't into a door problem because the mother can't say: OK first one was a boy/girl therefore the second one is of the opposite sex
Also, Mr. Biologist, the odds are not 50-50. There are slightly more girls on this world