heshamelaziry wrote:Q. 50% of elements in A are also there in B. Does A have more elements than B?
1) 40% elements of B are not in A
2) There are 30 elements which are present in B only and 20 elements which are present in A only.
No clue how to approach this
We know that half of A is in group B. However, we have no idea how much of B those elements fill up, so that's what we need to know to answer the question.
(1) 40% of the elements of B ARE NOT in A.
Flipping that around, we know that 60% of the elements of B ARE in A.
So, 60%(B) = 50%(A). From this we can determine the ratio of A to B... sufficient.
(2) if there are 20 elements present in A only, and half of A is in B, then there are 20 elements in A that are also in B. Therefore, A has a total of 40 elements.
We also know that there are 30 elements present in B only. Since B has 20 elements that overlap with A, B has a total of 50 elements.
Since we know the number of elements in both sets, we can certainly answer the question: sufficient.
So, the answer seems to be D.
HOWEVER, there's a big problem with this question. Based on the information in (1), A is a bigger set than B; based on the information in (2), B is a bigger set than A. So, (1) gives us a definite "YES" answer and (2) gives us a definite "NO" answer. On the real GMAT, this will NEVER happen. Therefore, this is a very poorly written question.
What's the source?
