In a monogamous culture, 100% of the adults are married. The average number of children per family is five and over-population is a threat. Programs to encourage birth-control have been ineffective. It has been suggested that this failure is due to these programs ignoring a tradition that values male children very highly, so that every parent wants to have at least one son. It is proposed that couples be encouraged to use birth-control measures after the birth of their first son.

If this proposal is widely accepted in the culture, we may expect that:

(A) the rate of population increase will be slowed, and future generations will contain a disproportionately high number of females.
(B) the rate of population increase will be slowed, and the gender balance in future generations will remain as it is at present.
(C) the rate of population growth will remain the same, and future generations will contain a disproportionately high number of females.
(D) there will be no significant effect either on population growth or on gender balance.
(E) the population will decline precipitously, because approximately half of all families will have only a single child.

A for me!
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proposal will cutdown the population

C,D are out

Population will dont decrease rapidly. E is out

A) the rate of population increase will be slowed, and future generations will contain a disproportionately high number of females.

B) the rate of population increase will be slowed, and the gender balance in future generations will remain as it is at present.

Unable to decide between A and B

assume there are 10 families trying to have a baby.say 6 families give birth to girls
m f
1st 4 6
the 3 families continue to try for a son
say 3 families give birth to girls
2nd try 3 3
the 3 families continue to try for a son
say 3 families give birth to girls
3rd try 0 3
the 3 families continue to try for a son
say 3 families give birth to girls

4th try 0 3

Iam inclining towards A

Thanks People! OA is BBB!

C can't be correct IMO...Think of it this way:

50% chance of getting a boy, 50% chance of getting a girl.

Two types of families. Those that get a boy first, and those that get a girl first:

If boy (50% chance), then take contraceptives (1 boy in family, no more reproduction after that)
If girl (50% chance), try again for boy. Most likely conclusion is 1 girl 1 boy (25%), slightly less likely is 2 girls 1 boy (12.5%), highly unlikely (6.25%) is 3 girls 1 boy.

Most likely result is:
Half all families will be 1boy only
Other half will be split predominantly "1 girl and 1 boy", with a portion being "2 girls 1 boy" and a much smaller portion being "3 girls 1 boy" and other even more unlikely divisions.

Overall the growth rate will slow down because now contraceptives will be adopted after the first son is born (as opposed to before when this was not actively encouraged)

Gender balance should remain about the same since the "power in numbers of boys" judging by the 50% of families with 1 boy only plus the 25% of families with 1 girl and 1 boy, will be somewhat driven down by the various other probabilities of "2 girls 1 boy, 3 girls 1 boy, etc..."

Hence, B

I hope this clarifies it... Its quite complicated for a CR :S

Most likely is that growth rate will go down and the gender balance will remain the same
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I am sorry but I do not see how B can be the answer. How are you able to say that the gender balance is going to remain the same?

I think if anything the Female population will be more than the male. Cause every family at the max stops after one male child , whereas with the female child you continue to procreate.

Also previous theory on 2:1 (F:M) , 3:1 (F:M) ....only is saying that the proportion is increasing.

what am I missing in this CR question. Any comments?

I chose C but I understand the error of my ways.

1) Each birth still has the same probability regardless of what gender was born in the past.
2) They will have less kids because if they get boys then they stop compared to before they just kept on going. =P

Therefore same ratios of M/F but less people.

I chose D ; if we assume that in the earlier case - the families didnt expand after getting their first male child - nothign changes after institituing the law as well. The only difference is ppl stop reproducing after getting frst male child. How is it different from what was happening earlier - unless it can be shown to be otherwise in which case I can agree that population growth rate may decrease.

very good question and durgesh79 explained it very well.

"... so that every parent wants to have at least one son. "

Here atleast suggests that, a parent might have more than one son also. If the proposal is widely accepted, there will be definetly decrease in the population...because the "atleast" become "atmost/equal to one son" for most of the families (Since, the proposal is widely accepted by many families)

We can eliminate, answer choices - C & D.

E: I think, probability here is not making sense in worst case scenario
B: No where in the argument mentioned that the majority of childers in the Average 5 are female.

A: Seems A is right to me.