780+ CR question #8

[selva.e]

780+ CR question
Source Beat the GMAT
http://gmatdarbaar.com/images/780Crs/etulip_100.jpg

[dhruv.sabharwal]

Is the answer 'C'?

[selva.e]

can you pls explain?

[ehu405]

Answer is E IMO.

Logic from the provided statement is as follows:

1. All Tulip Trees are older than Maple Trees
2. A majority of (i.e. but not all) Sycamore trees are older than Maple Trees
3. All Maple Trees are older than Dogwoods

A. Can't be true. If all Tulips are older than all Maples, then all Tulips would be older than all Dogwoods.

B. Because some Sycamores are not older than Maples, this could potentially be true. However, you can't be 100% certain.

C. Same logic as B. Has potential but can't be 100% certain.

D. Same logic as B & C. Has potential but can't be 100% certain.

E. This statement can't be negated. Rule #2 says only a majority of Sycamore trees are older than any Maple Tree. Thus, some Sycamore trees are either the same age or younger than any Maple Tree. Logically then, rule #1 (all Tulip Trees are older than any Maple Tree) makes it a certainty that some Sycamores are not as old as the youngest Tulip Tree.

[selva.e]

OA E

Thanks ehu405. Good Explanation

[RonPurewal]

this looks like an lsat problem. in any event, this problem is certainly not drawn from a repository of gmat problems.

you will almost certainly not see ANYTHING like this problem - which falls into the "formal deductive logic" category - on the gmat.