Manager
Joined: 09 Apr 2020
Posts: 121
Given Kudos: 570
Location: India
Concentration: Strategy, Entrepreneurship
GMAT 1: 690 Q49 V35
WE:Engineering (Other)
Re: If list S contains nine distinct integers, at least one of w
[#permalink]
08 Aug 2020, 05:02
Because list S has nine integers (an odd number), the median must be the middle integer.
(1) SUFFICIENT: The median is an integer. According to this statement, the nine numbers must collectively multiply to this same integer. None of the numbers is a fraction, and all nine are different numbers. The only way to multiply a bunch of integers together and arrive at the same starting point is to multiply by 0 or 1. In order to use 1, every number on the list except one would have to equal 1; for example, 1 × 1 × 1 × 3 = 3. In order to use 0, though, only one number has to equal zero; for example, 1 × 18 × -3 × 0 = 0.
Therefore, the only way in which the product of nine different integers can equal just one of the integers on that list is if the product of the nine integers is zero. (Not convinced? Try to disprove that rule using some real numbers. If the list is -4, -3, -2, -1, 1, 2, 3, 4, 5 then the median is 1 but the product is definitely not 1. If the list is -10, -9, -8, -7, -6, -5, -4, -3, -2, the median is -6 but the product is not -6. If, on the other hand, the list is -4, -3, -2, -1, 0, 1, 2, 3, 4, then the median is 0 and the product is also 0.)
Further, since the product of the nine integers equals the median, the median itself must also be zero. The median, then, is definitely not positive; the statement is sufficient to answer the question.
(2) INSUFFICIENT: The median of list S is one of the nine integers in list S. Therefore, if the sum of all nine integers equals the median, it follows that the sum of the eight integers on either side of the median must be zero:
Sum of all nine integers = (Median) + (Sum of other eight integers)
Statement 2 says that the Sum of all nine integers equals the Median. Substitute that info into the above equation:
Median = (Median) + (Sum of other eight integers)
0 = Sum of other eight integers
This isn’t enough, though, to determine the median; in fact, any number can still be the median of the list, as long as the surrounding numbers sum to zero. For example, the list –10, –9, –8, –7, 5, 7, 8, 9, 10 satisfies the criterion and has a median value of 5; the list –10, –9, –8, –7, -1, 6, 8, 9, 11 also satisfies the criterion and has a median value of -1.
The correct answer is A.