gmat prep DS

by **guest** Sun Mar 16, 2008 3:43 pm

is x+y < 1?
1. x< 8/9
2. y< 1/8

can someone explain this? thanks.

by **StaceyKoprince** Mon Mar 17, 2008 4:54 pm

Statement 1 is not sufficient because it says nothing about y. Elim A and D. Statement 2 is likewise not sufficient because it says nothing about x. Elim B.

1 and 2 together:
The upper limit for x is 8/9 (that is, x can be very close to 8/9, but it cannot actually be 8/9).
The upper limit for y is 1/8 (that is, y can be very close to 1/8, but it cannot actually be 1/8).

So to find the upper limit for x+y, add the limits together.
8/9 + 1/8 = 64/72 + 9/72 = 73/72. So:
x+y < 73/72
Could x+y be greater than one? Yes.
Could x+y be less than one? Yes.
So the info is not sufficient; answer is E.