swerve wrote:How many numbers do the sets \(S\) and \(T\) in common?

1) \(S\) is a set of 10 numbers.
2) \(T\) is a set of 100 numbers.

Target question: How many numbers do the sets S and T in common?

Statements 1 and 2 combined
There are several scenarios that satisfy BOTH statements. Here are two:
Case a: S = {1,1,1,1,1,1,..1,1} and T = {0,0,0,0,0.....,0,0,0,0,0}. In this case, the answer to the target question is sets S and T have 0 numbers in common
Case b: S = {1,1,1,1,1,1,..1,1} and T = {1,0,0,0,0.....,0,0,0,0,0}. In this case, the answer to the target question is sets S and T have 1 number in common
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent

swerve wrote:How many numbers do the sets \(S\) and \(T\) in common?

1) \(S\) is a set of 10 numbers.
2) \(T\) is a set of 100 numbers.

The OA is E

Source: GMAT Paper Tests

Statement One Only:

S is a set of 10 numbers.

Since we don't know anything about set T, statement one alone is not sufficient.

Statement Two Only:

T is a set of 100 numbers.

Since we don't know anything about set S, statement one alone is not sufficient.

Statements One and Two Together:

Even with the two statements together, we still don't have enough information to determine the number of numbers the two sets have in common since they could have no numbers in common or some (no more than 10) numbers in common.

Answer: E