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In a monogamous culture, 100% of the adults are married. The [#permalink]
23 Jun 2008, 21:05

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A

B

C

D

E

Difficulty:

85% (hard)

Question Stats:

21% (02:33) correct
79% (01:29) wrong based on 809 sessions

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.

clubzzang ur on a roll... one good question after the other...

+1 for this one too

Althouh Im not too sure, I would answer B for this...

As it is every parents wants atleast one son. Currently,they dont adopt birth control measures to have a son..

If one has to adopt birth control measures after they have a son.. the gender balance essentially remains the same, but the population may dwindle, as people adopt birth control measures after their first son..

lets assume probability of a birth of a male or female child is same 1/2....

So if the program is effective there'll be parents who'll stop at 1st, 2nd, 3rd ..... child, so the rate of population grwith will go down ... option C and D are out

even if half of the familes will have only one child, there'll be familes with more than 2 children also ... so option E is also out.

between A and B, I'd go for B, it wont effect the balance ...... Suppose there are 16 familes, so with a probability of 1/2, the birth of M and F child will have a pettern like this

First birth : 8M 8F Second birth : 4M, 4F (only with F in first round will go for second) Third birth : 2M, 2F (same logic as above) Forth birts : 1M, 1F

Total M = Total F = 15 ... so there will be a balance......

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

I was leaning towards E on a quick glance, but now I'm leaning more towards B

We will have two types of families:

1) Those who get a boy first (stop at 1 boy) 2) Those who get a girl first, then stop at the 1st boy after that

Assuming a 50/50 chance of getting a boy in the first place, we must assume that 50% of all the families will just have one boy. The other 50% will have 1+ girls and a boy

I don't see how the number of girls will be higher in the long run, hence I'm going for B. Although I must admit there are quite a few assumptions that should be made for this question (I hope I don't see a similar one on the actual GMAT!)

Other answers are clearly explained before my post.

Can you confirm which is the OA? _________________

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.

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 _________________

I was confused between A and B, finally ended up choosing A:(.

Where in the passage have we been told about the current state of gender balance/imbalance?? Are we not going out of scope of the premise on choosing B?

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?

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

gud eg by GMATobliterator bt not a convincing explanation. I think it is quite illogical 2 say that Gender balance should remain about the same. It u dig down deep in your eg u will find that there is a possibility that future generations (might) contain a disproportionately high number of females. both A and B are very close. _________________

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

It makes sense since families are already reproducing to the point of 1 male child anyways.

Using the probability of 1/2 for female and 1/2 for male.

The probability of having a female has no impact whatsoever on the following outcome. The next probability of having a female or male after having a female is still 1/2 and 1/2. And continues indefinitely. Just like flipping a coin. You cannot assume just because a family had a female the probability for a male goes up.

Family can have a 100 children and still never have a boy. This will not only keep the population the same, it might even increase.

I understand B. But I still would go with C on the test...

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.

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.

That was exactly how I interpreted it, initially. However, the question specifically says "if this proposal is widely accepted in the culture". To choose D is to assume that the proposal is not accepted.

"... 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.

GUys, if B is correct then how can we assume that gender balance will be same as present (with 5 kids per family) if people start using birth control after first son even if 50% use it?