IanStewart wrote:
In case this question is confusing for test takers, I'd point out that it doesn't make sense to pose a DS question in this way, for two reasons.
The first is a logical reason: it's not at all clear what information would be sufficient to answer a DS question set up this way. I can illustrate with a simpler example:
Of course, the information required is that x is integer. When x is integer, (x+3) and (x+10) can be treated as consecutive if we are looking at the remainder on division by 3. (x+3) will leave the same remainder as (x+3+3+3) or (x+9).
Now, three case..
1) case 1 - x+9 is divisible by 3 or leaves remainder 0, the term (x+3)(x+10) is divisible by 3.
2) case 2 - x+9 leaves remainder 1 when divided by 3 or , the term (x+3)(x+10) will leave 1*2=2.
3) case 3 - x+9 leaves remainder 2 when divided by 3 or , the term (x+3)(x+10) will leave 2*3=6 or 0.
SO 3 cases out of which 2 cases give us remainder 0. Probability = 2/3.
Also, you cannot take x as integer unless it is given, and GMAT will always give you that x is integer.
Quote:
Second, the GMAT will never ask "is y divisible by 6?" if y might not even be an integer. I've seen dozens of prep company questions where that's the supposed "trap" -- where a question asks "is k divisible by 5?" or "is k even?" where the "trap" is that k might not be an integer at all. The people designing those questions seem to be under the impression that if k is a non-integer, the answer to the question "is k divisible by 5?" is "no".
Of course, x divisible by 2 means x is even number, and not that it can be 3.6 as per GMAT.
Yes, you are correct that the questions so formed may not be exactly as per the actual questions. But one has to understand that the purpose of these questions is to teach the students not to read anything more than what is given in DS questions, and these questions do send that message very clearly and beautifully.
Although I would defer on the value of such questions, I would agree that actual questions may not be worded the same way.
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