Well this is a simple probability puzzle and most of the time people answer this puzzle correctly.
Let the number of couples in the country be X. So there will be X boys in the country as each couple will have one boy.
So probability of a girl child will be = 1* probability of one girl + 2* probability of two girls + 3 * probability of three girls + ...
number of girls = 0 + 1 x (0.5 x 0.5 x X) + 2 x (0.5 x 0.5 x 0.5 x X) + 3 x (0.5 x 0.5 x 0.5 x 0.5 x X) + number of girls = 0 + X/4 + X/4 + 3X/8 + .......
So if you solve this equation will approximation you will get
number of girls = X
So Ratio = 1:1
and the researcher is right as the ratio of girls to boys in the country will be same.
Let the number of couples in the country be X. So there will be X boys in the country as each couple will have one boy.
So probability of a girl child will be = 1* probability of one girl + 2* probability of two girls + 3 * probability of three girls + ...
number of girls = 0 + 1 x (0.5 x 0.5 x X) + 2 x (0.5 x 0.5 x 0.5 x X) + 3 x (0.5 x 0.5 x 0.5 x 0.5 x X) + number of girls = 0 + X/4 + X/4 + 3X/8 + .......
So if you solve this equation will approximation you will get
number of girls = X
So Ratio = 1:1
and the researcher is right as the ratio of girls to boys in the country will be same.
1 comments:
Ratio wont be same as:
1) If couple gives birth to boy,they will stop having babies.
2) If couple gives birth to girl,they will try have other baby.
So,girl:boy ratio will be 1:2
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