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Two men A and B walk from P to Q, a distance of 21 km, at 3 and 4 km an hour respectively. B reaches Q, returns immediately and meets A at R. The distance from P to R is
  • a)
    12 km
  • b)
    18 km
  • c)
    10 km
  • d)
    24 km
Correct answer is option 'B'. Can you explain this answer?
Most Upvoted Answer
Two men A and B walk from P to Q, a distance of 21 km, at 3 and 4 km a...
When B meets A at R, B has walked the distance PQ + QR and A the distance PR.
That is, both of them have together walked twice the distance from P to Q, i.e. 42 km.
Now, the speed of A and B are in the ratio 3 : 4, and they have walked 42 km.
Hence, the distance PR travelled by A = 3/7 of 42 km = 18 km.
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Community Answer
Two men A and B walk from P to Q, a distance of 21 km, at 3 and 4 km a...
Solution:

Let's break down the problem step by step:
1. Time taken by A and B to reach Q:
- Speed of A = 3 km/hr
- Speed of B = 4 km/hr
- Distance = 21 km
- Time taken by A = Distance/Speed = 21/3 = 7 hours
- Time taken by B = Distance/Speed = 21/4 = 5.25 hours
2. Meeting point R:
- When B reaches Q, he immediately returns towards P.
- By the time B reaches R, A would have covered a distance of 21 km.
- Since B takes 5.25 hours to reach Q and back, A covers 3 km/hr x 5.25 hrs = 15.75 km by the time they meet at R.
- Remaining distance from R to Q covered by B = 21 - 15.75 = 5.25 km
3. Calculating distance from P to R:
- Total distance from P to Q = 21 km
- Distance covered by A when B reaches Q = 21 km
- Distance covered by B from Q to R = 5.25 km
- Therefore, distance from P to R = 21 - 5.25 = 15.75 km
Hence, the distance from P to R is 15.75 km, which is closest to option B (18 km).
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Two men A and B walk from P to Q, a distance of 21 km, at 3 and 4 km an hour respectively. B reaches Q, returns immediately and meets A at R. The distance from P to R isa)12 kmb)18 kmc)10 kmd)24 kmCorrect answer is option 'B'. Can you explain this answer?
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Two men A and B walk from P to Q, a distance of 21 km, at 3 and 4 km an hour respectively. B reaches Q, returns immediately and meets A at R. The distance from P to R isa)12 kmb)18 kmc)10 kmd)24 kmCorrect answer is option 'B'. Can you explain this answer? for UPSC 2024 is part of UPSC preparation. The Question and answers have been prepared according to the UPSC exam syllabus. Information about Two men A and B walk from P to Q, a distance of 21 km, at 3 and 4 km an hour respectively. B reaches Q, returns immediately and meets A at R. The distance from P to R isa)12 kmb)18 kmc)10 kmd)24 kmCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for UPSC 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Two men A and B walk from P to Q, a distance of 21 km, at 3 and 4 km an hour respectively. B reaches Q, returns immediately and meets A at R. The distance from P to R isa)12 kmb)18 kmc)10 kmd)24 kmCorrect answer is option 'B'. Can you explain this answer?.
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