If the average of 11, 17, x and y is 19, what is the average of (x+5) and (y-7)?

A 46

B 23

C 21

D 14

Correct Answer: Option B

(11 + 17 + x + y)/4 = 19

or, (11 + 17 + x + y) = 19*4 = 76

or, x + y = 76 - 11 - 17

or, x + y = 48

Now,

[(x+5) + (y-7)]/2 = (x+5+y-7)/2 = [(x+y) -2]/2 = (48 -2)/2 = 46/2 = 23