Understanding Blood Relations from Coded Expressions

This question asks us to decode expressions representing family relationships based on a given set of rules and identify which expression signifies that 'P is the mother of R'. This type of problem tests our ability to interpret coded relations and trace family connections.

Decoding the Given Relationships

We are provided with the following rules for decoding the expressions:

• S - T means S is the mother of T.
• S × T means S is the father of T.
• S + T means S is the sister of T.

Our goal is to find the expression where P is the mother of R.

Analyzing Each Option

Let's analyze each given expression step-by-step to determine the relationship between P and R.

Analysis of Option 1: Q - P + R

• First part: Q - P. According to the rule S - T means S is the mother of T, this means Q is the mother of P.
• Second part: P + R. According to the rule S + T means S is the sister of T, this means P is the sister of R.
• Combining the relations: Q is the mother of P, and P is the sister of R. If P is the sister of R, they are in the same generation. Since Q is the mother of P, Q is also the mother of R.
• Conclusion for Option 1: This expression shows that Q is the mother of R. This is not what we are looking for.

Analysis of Option 2: P - Q + R

• First part: P - Q. According to the rule S - T means S is the mother of T, this means P is the mother of Q.
• Second part: Q + R. According to the rule S + T means S is the sister of T, this means Q is the sister of R.
• Combining the relations: P is the mother of Q, and Q is the sister of R. If Q is the sister of R, they are in the same generation. Since P is the mother of Q, P is also the mother of R.
• Conclusion for Option 2: This expression shows that P is the mother of R. This matches the required relationship.

Analysis of Option 3: P × Q + R

• First part: P × Q. According to the rule S × T means S is the father of T, this means P is the father of Q.
• Second part: Q + R. According to the rule S + T means S is the sister of T, this means Q is the sister of R.
• Combining the relations: P is the father of Q, and Q is the sister of R. If Q is the sister of R, they are in the same generation. Since P is the father of Q, P is also the father of R.
• Conclusion for Option 3: This expression shows that P is the father of R. This is not what we are looking for.

Analysis of Option 4: R + Q - P

• First part: R + Q. According to the rule S + T means S is the sister of T, this means R is the sister of Q.
• Second part: Q - P. According to the rule S - T means S is the mother of T, this means Q is the mother of P.
• Combining the relations: R is the sister of Q, and Q is the mother of P. This tells us that Q is the mother of P, and R is Q's sister. This does not establish P as the mother of R. In fact, P is a child of Q, and R is Q's sister, making R P's aunt.
• Conclusion for Option 4: This expression shows that Q is the mother of P. This is not what we are looking for.

Summary of Analysis

Let's summarize the relationships derived from each option:

From the analysis, only Option 2, P - Q + R, correctly represents the relationship where P is the mother of R.

Conclusion

Based on the step-by-step decoding of each option according to the given rules, the expression P - Q + R is the only one that shows P as the mother of R.

Revision Table: Blood Relation Coding

Additional Information: Solving Coded Blood Relation Problems

Coded blood relation problems are common in reasoning sections of competitive exams. Here are some tips for solving them effectively:

• Understand the Codes: Carefully note down what each symbol represents in terms of relationship and gender (if implied).
• Break Down the Expression: Analyze the expression segment by segment. For example, in A × B - C, first decode A × B, then use that result to decode the relationship with C.
• Draw a Family Tree (Optional but Helpful): For complex expressions, drawing a quick family tree diagram can help visualize the relationships and avoid confusion.
• Determine Gender and Generation: Pay attention to the gender of the individuals involved and their relative generations. Symbols like '-' and '×' usually determine the gender of the first person relative to the second, while '+' indicates a same-generation relationship.
• Work Backwards or Forwards: You can decode the expression from left to right or right to left, depending on what is easier for the specific problem.
• Check the Target Relation: Always keep the required relationship in mind while analyzing options.

Practicing various types of coded blood relation questions will improve speed and accuracy in solving these problems.