Puzzle of the Day: 80
Q, R, S and T are related to each other.
(1) T is Q’s brother or only daughter.
(2) Q or R is S’s only son.
(3) R or S is T’s sister.
(4) One of the four is the opposite gender from each of the other three.
How are they related to each other?
From (1) and (3), T can not be the only daughter and have a sister (R or S). Hence, T is T’s brother i.e. D is a Male. From (3), let’s say that R is T’s sister i.e. R is Female. From (2), Q is S’s only son i.e. Q is Male. But T is Q’s brother which means that Q is not S’s only son. Hence, our assumption was wrong. Thus, S is T’s sister i.e. S is Female. And R must be S’s only son. Now it is clear that T & R are Males and S is Female. Q must be a Male as only one of them is of opposite sex from each of the other three. And he is S & T’s brother.
S is the mother, Q is the son of S, T is the daughter of Q, R is the sister of T