Choi: All other factors being equal, children whose parents earned doc

Answer is C because:

Assume that of a population of 100 parents, 10% have children with PhDs. So there are 10 PhDs. (10% is reasonable because the number of PhD in a population is low, probably around 2%)

Hart's statement tells us that 3 of the 10 have parents who hold Phds and the other 7 do not.

Thus Hart's statement proves Choi's statement (that PhDs are more likely to have children that have PhDs)

The chance that a person without a PhD has a child with a PhD is 7/90

The chance that a person with a PhD has a child with a PhD is 3/10


* by the way, when one say something is more likely, it means that past data has shown that this claim to be true. i.e if I said, it is more likely that hurricanes follow a period of hot weather, it means that hurricanes have occurred more often after a period of hot weather than after a period of normal weather.

HI Perfectstranger,

The bolded part is the key. Choi is making a hypothetical statement--if all else is equal, then having parents is an advantage. Hart is making an empirical statement: he is discussing reality, in which all else isn't equal, and so his final results differ. This is entirely consistent with Choi's claim, since Hart is shifting the scope of the discussion from the theoretical to the practical.

Note that, in addition to the scope shift, a number/percent error may be present in Hart's claim. Take a look at ashah20's post for a great explanation. As is often the case on the GMAT, there are multiple ways to get to the correct solution!

Hi folks,

Excellent reasoning and critical thinking from all of you! Unfortunately, I'm afraid I need to be the bearer of bad news: its not (E).

(E) can be ruled out straightaway, in fact, simply by use of the word 'but' in the second half of the prompt. The two pieces of evidence are, at least superficially, contradictory; it's not correct to say Hart is supporting Choi.

That said, cano's reasoning was absolutely correct: the two statements aren't actually contradictory. There's not reason that both Hart and Choi's statements couldn't be true. Why is that?

The giveaway is in Choi's statement: All other factors being equal, doctoral parents predispose children to becoming doctors. Well, who's to say everything is equal? Choi is discussing the abstract, while Hart is providing statistic of what actually happens, in the real world where all isn't equal.

Thus, we can explain away the difference in the two statements. Parental influence is a factor in advanced education (so Choi is right) but it may not be a very important factor, one that can be overridden (resulting in Hart's statistics). (B), then, explains why both positions are factually correct.

Hope this helps!

so what do you mean by 'everything being equal' and how is everything not equal ?

Educational opportunities, money, career goals, and numerous other factors could influence a decision to attend a doctoral program far more than parents could. Choi ignores those factors, "All other factors being equal"; Hart, discussing real-world statistics, does not.

Which of the following sentence makes more sense:

Joey does not have nails or a hammer, so Joey cannot build a house.
Joey has nails and a hammer, so Joey can build a house.

The first one is solid but the second one seem iffy, right? Well, that's what E is saying. To build a house, you must have a hammer and nails; they are necessary tools to complete the process. But in addition to hammer and nails, you need lumber, paint, ladders, screws, electrical wiring, pipes, and siding. A hammer and nail are not sufficient to build a house, not by a long shot! And the second statement above mistakes a necessary condition for a sufficient one, so it is flawed.

However, as discussed above, neither Hart nor Choi make such a flawed premise; in fact, both of their statements are logically consistent. So choice (E), which describes a common reasoning flaw not present in this prompt, is wrong.

Hi Fritz,

"Consistent" does not mean "means the same thing as." It just means "does not contradict." And as you've pointed out in your reasoning, it is entirely possible (though by no means guaranteed) that Hart and Choi are both completely right! Their statements are consistent.

Regards,

Hi Fritz,

Sorry if I'm not understanding what you are saying. But if Choi's position is "in some cases" inconsistent with Hart's, then the two statements are certainly "consistent." When discussing logical arguments, "consistent" means simply "could both be true," and "inconsistent" means "cannot both be true." Since there are circumstances in which Hart and Choi's statements could both be true (even if in many--or most!--cases, they are not both true), the statements are consistent and (C) is correct. I hope this explains what I meant!

Regards,

Hi mourinhogmat,

"Necessity versus Sufficency" is tested far more often by the LSAT than on the GMAT. However, it is not something analogous to, say, sines and cosines on the Quant section (which will never be tested because they can't be solved intuitively or with "common knowledge.) It is a common logical flaw in life, along with "proportion vs. number" and "causation vs. correlation," and so it's fair game for the GMAT to test!

Tough question. IMO, C is correct.

The question is: Which of the following is the most accurate evaluation of Hart's reply
So we need to find an answer that must be true for what Hart replied. Don't be simply lured by signal words such as However, but, what more....... Make sure you understand the full context of the argument.

Choice: Children + parents earned doctorates ==> more likely to earn a doctorate than other children.
Hart: Over 70% of all doctorate holders do not have a parent also holds a doctorate.

Example:
There are 500 children,
30 children who have parent also hold doctorate. 20 children will earn doctorate ==> probability = 20/30 = 67%
570 other children, only 80 children will earn doctorate ==> probability = 70/570 = 14%

Clearly, Although 80% all doctorate holders do not have a parent that also holds a doctorate. they are less likely to earn a doctorate than children whose parents have doctorates (14% VS 67%)

==> Hart's reply is consistent with Choi.


How about other options. Why they are wrong?

(A) It establishes that Choi's claim is an exaggeration.
Wrong. Hart did not say Choi exaggerated.

(B) If true, it effectively demonstrates that Choi's claim cannot be accurate.
Wrong. Even Hart's reply is true, Choi's claim can also be true.

(C) It is consistent with Choi's claim.
Correct.

(D) It provides alternative reasons for accepting Choi's claim.
Wrong. There is no alternative reason.

(E) It mistakes what is necessary for an event with what is sufficient to determine that the event will occur.
Wrong. There are not necessary condition and sufficient condition in the argument. Moreover, Hart's reply is actually not a sufficient condition for Choi's claim.

Hope that helps.

It seems that pqhai has the right idea, but this is not how I came to the correct answer.

Lets try looking at it this way:

"Choi: All other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates.

Hart: But consider this: Over 70 percent of all doctorate holders do not have a parent that also holds a doctorate."


Example: Out of 125 parents, 25 hold PhD's and 100 do not

Lets say each parent has one child, and of those 125 children, 85 earn PhD's. If 70% of those 85 PhD holders are children of parents that do not have PhD's, this means that only 60/100 children whose parents do not have PhD's obtain a PhD. Thus, although 70% of PhD holders as Hart claims do not have parents with PhD's, 70% only constitutes 60% of the total population of children who have parents without PhD's. Thus, children of parents that do not have PhD's have a 60% chance of earning a PhD.

It then becomes clear that although the children of PhD holders constitute only 30% of the total number of PhD holders, it is clear that 30% of the 85 children who do earn a PhD from the pool of 125 is equal to 25, which means that 100% of the children of PhD holders earn a PhD in this particular case.

Thus, Hart's claim s consistent with Choi's because even if 70% of children that earn PhD's come from a non-PhD holding household, it is still only 60% of those children that earn a PhD in contrast to 100% of children who's parents have PhD's and constitute only 30% of the total PhD holding population. Thus, C is clearly the best answer.

It seems that the argument is based on the fact that there are far many more parents without PhD's than those with PhD's, thus the use of " All other factors being equal" by Choi seems to be a clue into this fact. "All things being equal" is an idiom that means"if things stay the way they are," a reference to the actual numbers on which the percentages are based and which to an American English speaker may seem more clear. So part of the difficulty of this question seems to derive from understanding this idiom as a clue into the fact that there are far fewer PhD's than people without PhD's because it is only in that context that the play of percentages makes sense. Therefore, Hart's claim is consistent with Choi's.

I hope this clarifies,

Albert


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This question is based on statistics so you have to be aware that percents depend on knowing the actual numbers.

Choi says if your parent has a doctorate you are more likely than the rest of the population to earn a doctorate. Hart claims that 70% of doctorate holders do not have a parent with a doctorate. The test writers want you to believe that more likely is related to the 70% but in fact those two are not related numbers. Once you understand that the issue is with the percents then it is time to eliminate wrong answers.

Hi vaibhavsharma,

As we discussed earlier, there is a different key phrase that you're missing--"likely to be" isn't really the central phrase.

The most important part of the prompt is the phrase "all else being equal." As soon as we see that, we know that one speaker is discussion hypothetical situations, and the other is discussing (unequal) reality. The two discussions are completely orthogonal to one another, and are therefore consistent (meaning not that they say the same thing, but rather, that they could both be correct at the same time)

Hope this helps!

Choi : childrens with doctoral parents more likely to become doctors than childrens with non doctoral parents

Lets say there are -
10 doctoral parents -(50% likely that their children will be doctors)- out of which 5 children doctors.
1000 non doctoral parents - 10% likely - 100 children doctor

total doctoral children = 105
Doctoral children with doctor parents = 5
Doctoral children with non doctor parents = 100

Hart: over 70% doctoral children have parents with no doctoral .

considering above highlighted data -
100/105 is the ratio/percentage of doctoral children with non-doctoral parent ( which is consistent with Hart - ratio is way over 70%).

This is more like a weighted average problem in quant.

Hence Hart's statement is consistent with Choi's .
-Jyothi

Hi hapless12,

GMAT questions (and LSAT style questions like this) are always structured to have a twist to them. The twist here is that set of contrast words you mentioned. The contrast words don't matter though because is what Hart says actually inconsistent with what Choi says? No.

What both Choi and Hart say could coexist, therefore we know for a fact that those two statements are consistent.

Its also important to note here that consistency doesn't mean supportive. It just means that the two statements can both be true, or in other words, that they don't disprove each other.

Much more to the bigger picture though, this is an LSAT style question by the way. Of all of the publicly released GMAC material, not a singe question has is remotely similar to this type. Questions like this do occur on the LSAT, however. That's why although certain LSAT questions can be helpful for the GMAT, many would be irrelevant for the GMAT. Its important to use caution when using LSAT or GRE practice questions to prepare for the GMAT. Each test has its own flavor.

A very cheap algebra data sufficinecy word problem, disguised as critical thinking problem.
Answer should not take more than a minute to reveal itself:- BY THE WAY THE CORRECT ANSWER IS C

THINGS YOU SHOULD KNOW BEFORE SOLVING THIS QUESTION:-
LESS LIKELY MEANS PROBABILITY IS 49% OR LESS THAN 49%
EQUALLY LIKELY MEANS PROBABILITY IS 50%-50%
MORE LIKELY MEANS PROBABILITY IS 51% OR MORE THAN 51 %


To start in a fair an unbiased manner :-
Assume there are 1000 parents.
500 parents have Phd. 500 DO NOT have PhD (Do not skew this ratio. Even though any ratio would give you the correct answer, you must solve these kind of question by assuming both sides are equal A=B and then you will not have to test other two cases A<B or A>B. After seeing the solution , try to solve this problem with any ratio you want and you will still get the right answer)


NOW STARTS THE REAL QUESTION (ALGEBRA + PROBABILITY)
WE WILL SOLVE ALGEBRA FIRST AND THEN MOVE TO PROBABILITY.

A) All other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates.
Parents with PHD = 500
More likely = 51 %
Children having PHD = 51 % of 500 = 255 PHD

B) Over 70 percent of all doctorate holders do not have a parent that also holds a doctorate.
Keep the term all doctorate in mind .
ALL doctorate means = (all kids= all whose parents have phd = 255)AND(kids whose parents have no phd=x)
The percentage of kids whose parents don't have phd is not given to us in the question stem. but we can easily find it
The percentage of phd kids whose parents don't have phd is x % of 500 (remember 500 parents don't have phd)= x% of 500 = (x/100)of 500 = 5x


now you know
Over 70 percent of all doctorate holders do not have a parent that also holds a doctorate.
70 % (255 +5x)=do not have parent that also holds a doctorate.
or
70 % (255 +5x)=non phd parent (how many non phd parents are there = 500 non phd parents)
70 % (255 +5x)=500
70/100 (255 +5x)=500
7/10 (255 +5x)=500
7 (255 +5x)=500*10 (we took 10 to the right)
7(255 +5x)=5000
1785+35x=5000
35x=5000-1785
35x=3215
x=3215/35
x=92
There are 92 kids who have phd but whose parents don't have phd.

NOW COMES THE PROBABILITY PART :-

92 KIDS HAVE PHD BUT THIER 500 PARENTS HAVE NO PHD
PROBABILITY OF KID HAVING PHD BUT PARENTS HAVING NO PHD = 92/500 = 18.4 %

255 KIDS HAVE PHD AND THIER 500 PARENTS HAVE PHD (We derived this as the very beginning of the question. remember the more likely to have phd clause.)
PROBABILITY OF KID HAVING PHD AND PARENTS HAVING PHD = 255/500 = 51%

This is what Hart said in her argument but in a different way.

Which of the following is the most accurate evaluation of Hart's reply?
(C) It is consistent with Choi's claim.

Choi: All other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates.
Hart: But consider this: Over 70 percent of all doctorate holders do not have a parent that also holds a doctorate.

Which of the following is the most accurate evaluation of Hart's reply?

(A) It establishes that Choi's claim is an exaggeration.
(B) If true, it effectively demonstrates that Choi's claim cannot be accurate.
(C) It is consistent with Choi's claim.
(D) It provides alternative reasons for accepting Choi's claim.
(E) It mistakes what is necessary for an event with what is sufficient to determine that the event will occur.

I wouldn't worry about this unofficial question too much. Choice (C) could be accurate (depending on the numbers), but this is not the type of thing you would see on the actual test.