Data Sufficiency

BTGmoderatorLU wrote:Source: GMAT Prep

Set X consists of different positive numbers arranged in ascending order: K, L, M, 5, 7. If K, L, and M are consecutive integers, what is the arithmetic of set X?

1. The product K*L*M is a multiple of 6
2. There are at least two prime numbers among K, L, and M

The OA is E

Target question: What is the arithmetic mean of set X?

Given: Set X consists of different positive numbers arranged in ascending order: K, L, M, 5, 7. K, L and M are consecutive integers
This means that EITHER K, L, M = 1, 2, 3 respectively, OR K, L, M = 2, 3, 4 respectively

Head straight to.....

Statements 1 and 2 combined
Notice that the two cases above satisfy BOTH statements. That is:
Case a: K, L, M = 1, 2, 3 respectively. In this case, the arithmetic mean of set X = (1+2+3+5+7)/5 = 18/5. So, the answer to the target question is 18/5
Case b: K, L, M = 2, 3, 4 respectively. In this case, the arithmetic mean of set X = (2+3+4+5+7)/5 = 21/5. So, the answer to the target question is 21/5
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent