What is the value of w+x+y+z?

[bhumika.k.shah]

Each of the numbers w,x,y and z is equal to either 0 or 1. What is the value of w+x+y+z?

(1) w/2+x/4+y/8+z/16=11/16

(2) w/3+x/9+y/27+z/81=31/81

Different and quicker approaches if this had been a PS sum?

Source GMAT prep

What difficulty level q is this?

[eaakbari]

IMO D

Statement one

(8w + 4x +2y +z)/16 = 11/16
which means
(8w + 4x +2y +z) = 11
The only way this is possible is if w,y and z =1
Hence suff

Statement two
same logic as above
suff

Hence D