Two men A and B start walking simultaneously from P to Q, a distance of 21 kms, at the speeds of 3 km and 4 km an hour respectively. B reaches Q, returns immediately and meets A at R. Then the distance from P to R is :
Solution
Correct Answer: Option C
Let the distance of R from Q be x km.
Thus, according to question
Time taken by man A to move from P to R = time taken by man B to move from P to Q and then return from Q to R
i.e. (21 – x)/ 3 = (21 + x)/ 4
⇒ 4(21 – x) = 3(21 + x)
⇒ 84 – 4x = 63 + 3x
⇒ 7x = (84 – 63)
⇒ 7x = 21
∴ x = 21/7 = 3 km
Thus, the distance from P to R is (21 – 3) = 18 km.
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