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If there are more than two numbers in a certain list...

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by BTGmoderatorLU » Mon Jan 13, 2020 7:08 pm
Source: GMAT Prep

If there are more than two numbers in a certain list, is each of the numbers in the list equal to 0?

1) The product of any two numbers in the list is equal to 0.
2) The sum of any two numbers in the list is equal to 0.

The OA is B
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Source: — Data Sufficiency |

Let list = L
L contains more than 2 numbers/elements
Question: Is each of the numbers/elements in the list L equal to 0?
Statement 1: The product of any two numbers in the list is equal to 0.
If the list L = {0, 0, 0}, all elements are equal to 0, and the product of any 2 elements equal to 0.
If the list L = {0, 0, 1}, all elements are not equal to 0, and the product of any 2 elements equal to 0
The information provided in this statement gives room for at least one element in list L not to be equal to 0, and if it also possible for all elements to be equal to 0.
Hence, statement 1 is NOT SUFFICIENT.

Statement 2: The sum of any two numbers/elements in the list L is equal to 0.
If the elements in list L are just 2 elements, then for their sum to be equal to 3, it is possible that the 2 elements will not be 0. E.g. -3 and +3.
Since there are more than 2 elements/numbers in the list L, then only for the sum of any two numbers/elements to be equal to 0 is if all elements in the list L are equal to 0. With the information provided here, each of the numbers in the list is equal to 0. Therefore, statement 2 is SUFFICIENT.

Since statement 2 alone is SUFFICIENT, then, the correct answer choice is option B.
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