Data set M consist of distinct negative integers. What is the value of

Par of GMAT CLUB'S New Year's Quantitative Challenge Set

Lets see what we can observe from the question stem.

First, set M can look something like this: M={-1, -2, -3...} but we don't actually know what numbers it will have. Second, if at all the set does look like our example, the greatest number in the set will actually be -1. These two observations are important to keep in mind so that we don't make silly mistakes while actually solving the question.

Statement 1: If every number to be product of -1 and a prime number, we can have set M to look like this: M={-2, -3, -5..}. Notice that we don't include -1 here since 1 is neither prime nor composite and hence -1*1 is not included. Additionally, notice that are not sure if M will in fact contain these numbers because M could also look like this: M={-17, -19, -23..}. Thus, because we cannot necessarily ascertain the greatest number in the set, this statement is insufficient

Statement 2: This statement again gives us many possibilities of what M could look like. It could be M={-2, -5, -7...} or even M={-17, -20, -21..}. Again, this statement is insufficient

If we combine statement 1 and 2, we certainly get -2 in the set. This is because -2 satisfies statement 1 (-1*2 (=prime number)) and satisfies statement 2 (-2 is the only even number that will be in the set defined by statement 1.

Thus answer is C

i dont agree with the solution. Because nowhere it is mentioned that, the set contains only one even number. So we cant assume that if we combine both the statements, there will be only one even number and that is -2. the answer is really ambiguous and it should not be C.

That's not correct.

The stem says that "Data set M consist of distinct negative integers". Next, (1) says that "Every number of set M is the product of -1 and a prime number", so the set consists of numbers which are of a form of -1*prime. So, possible elements of the set are -2, -3, -5, -7, -11, ... Notice that the set can have only one even number, namely -2 because no other negative even number can be written as -1*prime. (2) says that "One of the numbers in set M is even". When combining we know that the even integer of the set must be -2. And since all other possible elements of the set are less than -2 (-3, -5, -7, -11, ....), then the greatest number in the set must be -2.

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