UPSC CSE Prelims 2022
Consider the questions and two statements given below:
Question: Is Z brother of X?
- Statement 1: X is a brother of Y and Y is a brother of Z.
- Statement 2: X, Y and Z are siblings.
Which one of the following is correct in respect of the question and statements?
EXPLANATION
Correct Option (4)
: Both Statement 1 and 2 are not sufficient to answer the question.
To answer the question "Is Z brother of X?", the gender of Z must be definitively established as male, in addition to Z being a sibling of X.
- Analysis of Statement 1: "X is a brother of Y and Y is a brother of Z."
- This implies X is male, and Y is male.
- It also establishes that X, Y, and Z are siblings.
- However, Statement 1 provides no information regarding the gender of Z. Z could be either a brother or a sister to X.
- Therefore, Statement 1 alone is insufficient.
- Analysis of Statement 2: "X, Y and Z are siblings."
- This statement confirms a sibling relationship among X, Y, and Z.
- However, it provides no information about the gender of any of the individuals (X, Y, or Z).
- Therefore, Statement 2 alone is insufficient.
- Analysis of Statement 1 and Statement 2 combined:
- Even when both statements are considered together, the gender of Z remains undetermined. While it is known that X, Y, and Z are siblings, and X and Y are male, Z's gender is not specified by either statement or their combination.
- Consequently, it cannot be definitively concluded whether Z is a brother or a sister of X.
- Thus, both statements together are insufficient to answer the question.
Incorrect Options:
Option 1: Statement 1 alone is sufficient to answer the question.
Statement 1 establishes X and Y as male siblings, and that Z is their sibling. However, it does not specify Z's gender, making it impossible to confirm if Z is a brother. Hence, it is insufficient.
Option 2: Statement 2 alone is sufficient to answer the question.
Statement 2 only indicates that X, Y, and Z are siblings. It provides no information about the gender of any of them. Therefore, it is insufficient to determine if Z is a brother of X.
Option 3: Both Statement 1 and 2 are sufficient to answer the question.
As detailed in the analysis of the correct option, even combining both statements does not provide information about Z's gender. Without knowing Z's gender, it cannot be determined if Z is a brother of X. Hence, both statements together are insufficient.
