P and Q are sisters. R and S are brothers. The daughter of P is the sister of R. What is the relation of Q to S?

Introduction / Context:
This blood relation question combines two pairs of siblings and a child to test whether you can correctly place everyone in a family tree. The challenge is to understand how the daughter of P being the sister of R connects P and Q to R and S, and then to identify the correct relation between Q and S.

Given Data / Assumptions:

• P and Q are sisters, so they are in the same generation and both female.
• R and S are brothers, so they are in the same generation and both male.
• The daughter of P is the sister of R.
• Being sisters means that P daughter and R share the same parents.
• We assume full siblings with the same two parents unless otherwise stated.

Concept / Approach:
The key idea is that if P daughter is the sister of R, then P must be a parent of R or married to a parent of R. That makes P the mother of R and S in typical exam style reasoning. Once that is clear, Q, being P sister, becomes the maternal aunt of R and S. The question then asks for the relation of Q to S, which is aunt.

Step-by-Step Solution:
Step 1: Let P daughter be called D for clarity.Step 2: The statement says that D is the sister of R. This means D and R are children of the same parents.Step 3: One of those parents is P, because D is the daughter of P. Hence P is a parent of D and, by the shared parent assumption, also a parent of R.Step 4: Since R and S are brothers, S is another child of the same parents who gave birth to R. Therefore, S is also a child of P and P spouse.Step 5: Thus P is the mother of R and S, and P daughter D is their sister.Step 6: Q is the sister of P. Since P is the mother of S, Q is P sister and therefore S maternal aunt.Step 7: The question asks, "What is Q relation to S?" So the answer is aunt.

Verification / Alternative check:
Assign sample names. Let P and Q be sisters named Preeti and Quena. Let Preeti have a daughter, Dia. We are told that Dia is the sister of R. For Dia and R to be siblings, they must share the same parents, which include Preeti. So Preeti is also R mother. S is the brother of R, so S is another child of Preeti. Hence, Quena is the sister of S mother. From S point of view, Quena is his maternal aunt. This matches our conclusion.

Why Other Options Are Wrong:
Q cannot be S mother because that role is already taken by P. Q cannot be the grandmother, because she is in the same generation as S mother, not one generation above. She is not S own sister, because they are in different generations. Cousin is also incorrect because cousins are children of siblings, not siblings of parents of someone.

Common Pitfalls:
A common error is to assume that if P and Q are sisters, then Q must be a kind of mother figure to S, but that ignores the information that P daughter is R sister. Another mistake is to forget that R and S are brothers and therefore share the same parents, which forces S to be a child of P as well. Drawing a small diagram with generations labelled usually prevents these mistakes.

Final Answer:
Q is related to S as his aunt.