Data Sufficiency

BTGmoderatorDC wrote:If 500 is the multiple of 100 that is closest to X and 400 is the multiple of 100 closest to Y, then which multiple of 100 closest to X + Y?

(1) X < 500

(2) Y < 400

Statements combined:
Case 1:
X=460, with the result that 500 is the multiple of 100 closest to X
Y=360, with the result that 400 is the multiple of 100 closest to Y
In this case, X+Y=820, so the multiple of 100 closest to X+Y is 800.

Case 2:
X=490, with the result that 500 is the multiple of 100 closest to X
Y=390, with the result that 400 is the multiple of 100 closest to Y
In this case, X+Y=880, so the multiple of 100 closest to X+Y is 900.

Since the multiple of 100 closest to X+Y can be different values, the two statements combined are INSUFFICIENT.

The correct answer is E.