In a country where everyone wants a boy, each family continues having babies till they have a boy. After some time, what is the proportion of boys to girls in the country? (Assuming probability of having a boy or a girl is the same) Choose the correct choice from the following.
A) 1:2
B) 3:5
C) 1:1
D) 3:7
E) 2:4
C   1:1   This is a very simple probability question in a software interview. This question might be a little old to be ever asked again but it is a good warm up.   Assume there are C number of couples so there would be C boys. The number of girls can be calculated by the following method.   Number of girls = 0*(Probability of 0 girls) + 1*(Probability of 1 girl) + 2*(Probability of 2 girls) + …   Number of girls = 0*(1:1*1/2) + 1*(1:1*1/2*1/2) + 2*(1:1*1/2*1/2*1/2) + …   Number of girls = 0 + 1:1/4 + 2*1:1/8 + 3*1:1/16 + …   Number of girls = 1:1   (using mathematical formulas; it becomes apparent if you just sum up the first 4-5 terms)   The proportion of boys to girls is 1 : 1.
<result>C</result>
In a country where everyone wants a boy, each family continues having babies till they have a boy. After some time, what is the proportion of boys to girls in the country? (Assuming probability of having a boy or a girl is the same)