Jihyo wrote:
hello..
Bunuel AndrewN math Revolution
chetan2u How do we assume his age is an integer?
Hello,
Jihyo. First of all, it is an honor to be mentioned alongside such Quant luminaries. That said, I think the problem with the question is that the language used is unclear and leaves the test-taker to make assumptions that lead to the desired answer, something the GMAT™ would never require of the test-taker. You ask a fair question about an integer value, since nowhere does the problem or question stem specify this. (65.0005 seems valid, for example.) The larger issue to me is that the question stem is lacking an adverb that would make it clear that we need to consider all three estimates
together. Compare:
1) Actual question—
all are them are correct in their estimation2) Revised question—
they are all collectively correct in their estimationThe first question stem leaves the door open for
each estimate to considered valid, as in,
- Arun: 65kg < weight < 72
- Brother: 60kg < weight < 70kg
- Mother: 0kg < weight </= 68kg
By way of analogy, it would be like my pointing to a rainbow and saying it was red, but another person yellow and a third person blue. We could say that all of us were correct within the range of colors of a rainbow.
Meanwhile, the revised question stem encompasses the three estimates
together, restricting the range of values. We can now appreciate that the lower limit is 65kg (not inclusive) while the upper limit is 68kg (inclusive). But since we should not assume integer values unless the question specifies such a restriction, we cannot say that (A) must be the answer.
I would not worry too much about the question, to be honest. I can think of zero official questions that would incorporate an answer such as (D). An official question would also be vetted to ensure that a single valid answer was possible. (I have seen just one or two exceptions over the years.)
- Andrew
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