Persons X, Y, Z and Q live in Red, Green, Yellow and Blue colored houses which are in a sequence on a street. Z lives in a Yellow house. The Green house is adjacent to the blue house. X does not live adjacent to Z. The yellow house is in between the green and red houses. The colour of the house, X lives in is:

Blue

Given: Z lives in a Yellow house.

We have 2 cases;

(I);

BLUE (X could be here),  GREEN (Y/Q),  YELLOW (Z),  RED (Y/Q)

(II);

RED (Y/Q),  YELLOW (Z),  GREEN (Y/Q),  BLUE (X could be here)

Thus, "Blue" is correct.