Critical Reasoning

In a monogamous culture, 90% 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.

If the plan is effective the population is gowing to slow down. Couples will have only one son. (If they only have 1 kid and if its a son, then its less than the earlier scenario when the couples would aspire and have more than 1 son).
Secondly, according to the plan the couples can have more than 1 daughter but only one son. So it will cause the female population to go high.

This is tricky and I'm going with (D).

Everything will remain as it is ; there would be no change in in population or gender balance.

Boy this is a tricky one ..

I had to choose between C and D and I chose C .. because in all probabilities - the parents will keep having kids until they have a Son - so the number of females will increase, unless a vast majority of the parents had a son as their first child.

I vote for C

IMO B and D are contenders, finally I choose D

Son = S
Daughter =D

BEFORE THE PROPOSAL:

DSDSDSDSDSDS....

AFTER THE PROPOSAL:

DDDS

S

DS

well there is one thing we can infer that there will LESS males!

Growth might stay the same but there will be less MALES.



C) the rate of population growth will remain the same, and future generations will contain a disproportionately high number of females.

I go with E, at least 50% of families will have only single child and this will reduce the rate of growth drastically.

The way I looked at this was:

Say you had a 100 families. Before the plan, they all have 5 kids. We can expect:

Round 1: 50 Males, 50 Females
Round 2: 50 Males, 50 Females
Round 3: 50 Males, 50 Females
Round 4: 50 Males, 50 Females
Round 5: 50 Males, 50 Females

So we end up expecting 250 males and 250 females.

After the policy, if it's successful we can expect:

Round 1: 50 Males, 50 Females (only 50 families keep trying for a male)
Round 2: 25 Males, 25 Females (only 25 families keep trying for a male)
Round 3: 12.5 Males, 12.5 Females (only 12-13 families keep trying for a male)
<trend continues>

So we end up with less children but they remain in a 50/50 proportion.

As a result I think the answer choice is E.

IMO E

First, we can all agree that population growth will decrease because of the new proposal, so D is out. But we don't know whether a) people will have a string of girls then stop at the first boy they get, or b) the first kid will be a boy then they stop because they have to use birth control. This eliminates A, B, and C because we can't predict the gender numbers.

Each birth has a 50-50 chance of being a boy (or girl). So if there's a 50% chance of getting a boy, then each family has a 50% chance that they will have a single kid, because they'll have to use birth control after a boy. Answer E doesn't make any predictions on the gender numbers but just gives an explanation of why the population will decrease - "the population will decline precipitously, because approximately half of all families will have only a single child".

logitech wrote:Son = S
Daughter =D

BEFORE THE PROPOSAL:

DSDSDSDSDSDS....

AFTER THE PROPOSAL:

DDDS

S

DS

well there is one thing we can infer that there will LESS males!

Growth might stay the same but there will be less MALES.



C) the rate of population growth will remain the same, and future generations will contain a disproportionately high number of females.

you sure?

OA plz...

E here too !! .. buddy , pls OA daaaa .. pls.. need it very badly..pls vscid

As per Ms. Nandy's command, here's the OA and pseudo OE.

OA is B.

I do not have an official explanation (although I have read it), but it may be close to something like this:

The 2 events, producing a boy and producing a girl, are independent events.
So the probability of having a boy or a girl is 1/2 at any given time.

Hence, on an average, half of all families will produce their first child: a boy ,then stop.
Thus, half of all families have 1 boy. (lets say 'X' number of families)

The other half will produce their first child: a girl.(lets say 'Y' number of families)
However, they do not stop here.

They go on to produce another one in the hope of getting a boy.

Out of this other half (Y), a portion produces, 1G and then 1B and stop.
A smaller portion (than one above) from Y produces 1G+1G+1B and stop.
A still smaller portion (than one above) produces 1G+1G+1G+1B and stop.

Eventually, the numbers on each side (boy's and girl's) balance out.

Consider, this to follow the law of averages. (While the law of averages is not backed by a mathematical principle, it can be considered to be fairly approximate for large numbers)

what is the source ?