School official: The rate of childhood obesity in Paceville has decrea

Question

School official: The rate of childhood obesity in Paceville has decreased by 50% in the last five years, whereas the rate of childhood obesity in Aratown has increased by 50% in the same time period. Children in the town of Paceville are obviously much less likely to be obese than are children in Aratown.

This argument fails to consider which of the following questions?

A. How many children were obese in Paceville and Aratown five years ago?

B. Were rates of childhood obesity in Paceville higher than those in Aratown five years ago?

C. Has there been any migration between Paceville and Aratown in the last five years?

D. What were the rates of childhood obesity in Paceville and Aratown five years ago?

E. What percent of children are likely to remain obese for five years or more?

Bunuel · Accepted Answer

VERITAS PREP OFFICIAL EXPLANATION:

Whenever a question asks you what an argument "fails to consider," it is asking a weaken question. And as with any weaken question, your strategy should be to understand the argument given and find the gap before you move on to your answer choices.

You are told that Paceville's rate of childhood obesity decreased by 50% during the same time period that Aratown's childhood obesity rate increased by 50%. The official then claims that this is sufficient evidence to conclude that Paceville children are less likely to be obese than are Aratown children. However, notice that the argument only gives you information on the percent change in the rates of the two towns without giving any information about the original rates of childhood obesity in each town.

So while the conclusion would be valid if the two towns had started with similar rates of childhood obesity, it would be invalid if, for example, Aratown had originally had a childhood obesity rate of 2% and Paceville had a childhood obesity rate of 50%. Under those circumstances, Aratown would still only have a 3% childhood obesity rate after a 50% increase, whereas Paceville would have a 25% childhood obesity rate after its 50% decrease. This demonstrates the need for choice (D) - the only way to conclude whether the official's claims are valid is to know the actual rates of childhood obesity in each town five years ago.

Both (A) and (B) are close but do not give quite enough information to determine whether the argument is valid. Since the question asks about the rate of childhood obesity rather than numbers of children (A) does not give enough information. Similarly, (B) can be eliminated because you don't have enough information even if the question is answered. If Paceville had a rate of 20% and Aratown had a rate of 19%, then the claim would be true. However, if Paceville had a rate of 20% and Aratown had a rate of 2%, then the claim would be false.

Between the other two answers, choice (C) can be eliminated because migration is not relevant to the claim posed, and choice (E) can be eliminated because whether the same children are overweight or not is not a factor in the information being measured.

Nikhil · Answer

Prethinking  : The school official specifies the percentage decrease and increase in the rate of childhood obesity but didn't specify anything about the actual population in the two towns. There could be the case where some population moved from Paceville to Aratown causing the rate of obesity to decrease and increase respectively.

A. How many children were obese in Paceville and Aratown five years ago?

The author specifies the percentage change in the obesity rates which include the number of obese children five years ago. Hence this statement was considered in authors conclusion.  INCORRECT

B. Were rates of childhood obesity in Paceville higher than those in Aratown five years ago?

The comparison of the rates between two towns doesn't affect the authors conclusion which only presents the individual obesity rates for two towns.  INCORRECT

C. Has there been any migration between Paceville and Aratown in the last five years?

If there was a migration between Paceville and Aratown, then the authors conclusion seems to be invalid. Hence the author should have addressed this.

D. What were the rates of childhood obesity in Paceville and Aratown five years ago?

The obesity rates five years ago doesn't affect the obesity rates today. Hence this doesn't contribute to the authors conclusion.  INCORRECT

E. What percent of children are likely to remain obese for five years or more?

This option doesn't affect the conclusion made by the author regarding the obesity rates today. Hence there is no need for the author to consider this  INCORRECT

Hence option C

ankitsaroha · Answer

D

The argument talks about the increase/decrease in the rate of obesity and concludes that the current percentage of obese children in Aratown is higher than the current percentage of obese children in Paceville.

The changes in rates are not enough to find out the current rate. We also need to know the initial values of the rates.
If the initial rate of Aratown was 1% and the initial rate of Paceville was 80%, then the argument fails.
So, we do need the initial rates.

A - Number of obese children 5 years ago cannot help us to find the number of obese children now. We need the total population too.

B - If the rate in Paceville was 50% and rate in Aratown was 40%, then the current rates would be 25% and 60%. So, rate in Aratown is higher than the rate in Paceville. But if the respective rates were 80% and 10%, then the current rates would be 40% and 15%. In this case the rate in Aratown is lower.

C - Migration between Paceville and Aratown doesn't matter. It is possible that some obese children migrated from Paceville to Aratown, hence the decrease/increase in the respective towns, but we still get no information about the current rates of obesity.

D - This is what we need.

E - We are not concerned about the future.

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GmatDaddy · Answer

I got this question wrong! Chose Answer Choice A!
 I guess likeliness interprets to the rate/percentage.

Had the Question stem been:
School official: The rate of childhood obesity in Paceville has decreased by 50% in the last five years, whereas the rate of childhood obesity in Aratown has increased by 50% in the same time period.  More children in Aratown are likely to suffer from childhood obesity than in Paceville.

Will then the Answer Choice A, be a better one ?

ankitsaroha · Answer

You would still need the total population of each town in the respective year. You cannot find the current number of obese children just by knowing the initial number and the change in rates.
Say, 100 children were obese 5 years ago, and the rate of obese children has decreased by 50%. Can you find the current number of obese children? No. You don't know 100 was what percentage of the total population. If the total population 5 years ago was 500, and it is 1000 now, without any change in the number of obese children, the rate has changed from 20% to 10% - a decrease of 50%. But if the population remains same (500) and the number of obese children decreases from 100 to 50, then also the rate changes from 20% to 10% - a decrease of 50%. You end up with different numbers in the two cases.

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Mo2men · Answer

Dear  GMATGuruNY

Can you please share your thoughts on this question?

In some OG Weaken questions, the correct answers fail to consider the real number of set included in the data and hence could weaken the question.

Thanks in advance

GMATGuruNY · Answer

Consider the following case:
Over the past five years, Aratown's childhood obesity rate has increased from 2% to 3%, a 50% increase.
Over the past five years, Paceville's childhood obesity rate has decreased from 6% to 3%, a 50% decrease.
The result:
Each town currently has the SAME childhood obesity rate: 3%.
Implication:
If Paceville's rate five years ago was exactly three times Aratown's rate five years ago -- in the case above, 6% versus 2% -- then children in the two towns currently have the same likelihood of being obese.
For Paceville's likelihood to be much lower than Aratown's, it would have to be true that -- five years ago --  Paceville's childhood obesiity rate was MUCH LESS THAN THREE TIMES Aratown's childhood obesity rate .
Only the answer to D will enable us to determine whether the statement in blue is true.
Thus, the argument is flawed because it fails to consider D.

D

Cubie · Answer

Hi,

I think the catch here is : The stimulus states that the 'rate' of childhood obesity has increased/decreased by 50%. Note that the rate is already a % value. So to evaluate the likelihood of a person being obese, we would need to know the rates of childhood obesity in Paceville and Aratown five years ago (thus option D is correct).

If the stimulus had stated that the 'number of obese children increased by 50%' , we would need to know the number of obese children 5 years ago. (and option A would have been correct).

Experts please correct me if I am wrong.

Please +1 KUDO if my post helps. Thank you.

TaN1213 · Answer

Hello Experts,

In this question, can you please clarify why is A wrong? Does "Likelihood" depends upon rates only? And what does "rate" signify here? 
Thank you in advance.

Aviral1995 · Answer

Let me try to answer your question 
In A we would just have absolute numbers of the number of people who are obese in Town P and Town A. Since we donot have an absolute value of the total number of children, we have no information about the percentage of people obese

Hope it helps.

gambit07 · Answer

I don't understand why some of the answers posted here are trying to justify D without considering base numbers i.e. # of obese children five year ago.

princevora · Answer

Final elimination between A&D, eliminating A because even if we know the number of obese children we can not tell the probability (likelihood) of obese children unless we know initial rates/ total number of children. But if we know initial rates it is sufficient to tell us the actual likelihood.

sghosh1096 · Answer

School official: The rate of childhood obesity in Paceville has decreased by 50% in the last five years, whereas the rate of childhood obesity in Aratown has increased by 50% in the same time period. Children in the town of Paceville are obviously much less likely to be obese than are children in Aratown.

can someone tell me why A is not the correct option?
we are told children in town P(-50%) are much less likely to be obese than town A (+50%).

say if P had 50 obese children and A had 10 obese children 5 years ago.
shouldn't P now have 25 obese children while A has 15 obese children?

bb · Answer

Hi. This is a tricky question and it’s more mathematical than most CR’s.

You are correct that if we find out the number of children who had obesity, that could tell us which town has the most and if one had 1000 and the other one had only 10 then it would be a big difference.

However, even if you found out that one Town has 1000 of these children and the other one had only 10, you do not know the size of those towns and how many total children there are. Similarly, the town that has 1000 the beast children may have 1 million people living at and the town that has 10 may only have 100 so the busy rate can vary wildly depending on those numbers, and since we want to know specifically the rate not the total number, A does not work.

School official: The rate of childhood obesity in Paceville has decrea

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School official: The rate of childhood obesity in Paceville has decrea

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