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Railways PYQCBT 2 2017

RRB NTPC · Question 67

Two buses start from a house at an interval of 5 minutes and move with a speed of 10 km/hr in the same direction. With how much speed (km/hr.) should a woman coming from the opposite direction towards the house travel, to meet the buses at an interval of 3 minutes?

  1. 6.5

  2. 6

  3. \(6 \dfrac{1}{3}\)

  4. \(6 \dfrac{2}{3}\)

Show answer & explanation

Answer: (D) \(6 \dfrac{2}{3}\)

Explanation

Buses 5 minutes apart at 10 km/h are 10 × 5/60 = 5/6 km apart. Meeting them every 3 minutes: (10 + v) × 3/60 = 5/6, so 10 + v = 50/3 and v = 20/3 = 6 2/3 km/h.