Data sufficiency: Ravi's age from his older brother's
Data sufficiency: Ravi's age from his older brother's: Question: What is Ravi's age? Statement I: Ravi is 8 years… Answer and worked solution on CodeKairo.
- Topic: Mathematical Reasoning
- Section: Logical Reasoning
- Difficulty: Medium
- Time target: 90 seconds
Question
Question: What is Ravi's age?
Statement I: Ravi is 8 years younger than his brother. Statement II: Ravi's brother will be 30 in five years.
Which statements are needed?
Options
- I alone is sufficient
- II alone is sufficient
- Both together are needed
- Even both together are not sufficient
Show the answer and the worked solution
Correct answer: C. Both together are needed
Worked solution
- I alone: a relation but no number — not sufficient.
- II alone: the brother is 25 now, but nothing links that to Ravi — not sufficient.
- Together: brother 25, so Ravi is 17. Both together are needed.
Answer: Both together are needed.
The idea
Evaluate each statement in isolation first, carrying nothing across. The question asks about sufficiency, not the value itself.
Shortcut. Spot what each statement lacks: I has no number and II never mentions Ravi. Each supplies the other's missing piece (brother 25, so Ravi 17), so both are needed.
Common trap. "II alone is sufficient" — II gives a firm number (the brother is 25 now), and the hurried reader silently borrows 'Ravi is 8 years younger' from I.