In the decimal above, each of X and Y represent a single

my bad, you are correct.

(1) The sum of the digits X and Y is 5.

---> it could by any combination of (0,5) ( 1,4) (2,3), (3,2),(5,0)(4,1)

so can not pick x

(2) The result of rounding the decimal number to the nearest thousandth is 7.185.

--->the number ws 7.184 and it got rounded to 7.185 =====> the unit digit should be either 5 or more than 5

i can not say wht is the value of x.

but if i combine both, would get the ans as : C

Ok.. the answer is indeed C... I just realized how dumb I am

The answer is C. Remember when testing the statement 2, to forget completely about statement 1. You may end up choosing B instead of C.

There are serious problems with this question. Clearly the intended answer is C, but that would mean our number is 7.81450. There are two problems with this:

* if you have the number 7.81450, then you don't normally write the final zero; that number is 7.8145. A test taker could very reasonably assume that y is nonzero here and quite legitimately choose A as the answer.

* More importantly, you can't round the number 7.8145 to the 'nearest thousandth'; it's equally close to 7.814 and 7.815. Whether you round this to 7.814 or to 7.815 depends on which rounding conventions you are using, and those conventions are different in different contexts (in American education, children are often taught to round up in this case, but that is definitely *not* generally true in real mathematics). The GMAT will never ask about rounding off a number that is exactly halfway between two potential candidates -- you won't be asked to round 1.5 to the nearest integer, for example -- because depending how you learned rounding, you could give three different completely legitimate answers: 1, 2 or 'it can't be done'.

This is just a badly designed question.

Edit: I guess all of my issues with the question would be resolved if the number they asked about was something like "7.184XY4" instead of "7.184XY". If they add one nonzero digit after the 'Y', there's nothing wrong with the question.