Mean, Medium, SD Question

Hi Everyone,

This is my first post and I have a question on the following problem on mean, medium, and standard deviation:

The table below represents three sets of numbers with their respective medians, means and standard deviations. The third set, Set [A+B], denotes the set that is formed by combining Set A and Set B.



Set A ____ X (Mean) Y (Medium) Z (SD)
Set B ____ L (Mean) M (Medium) N (SD)
Set [A + B] _____ Q (Mean) R (Medium) S (SD)

If X – Y > 0 and L – M = 0, then which of the following must be true?

I. Z > N
II. R > M
III. Q > R


I only
II only
III only
I and II only
none


Is there a general rule that I can use to solve this quickly instead of listing out possible examples?

Thanks