Question

A person walks a distance from point A to B at 15 km/h, and from point B to A at 30 km/h. If he takes 3 hours to complete the journey, then what is the distance from point A to B?

• A. 30 km
• B. 25 km
• C. 10 km
• D. 15 km

Answer 1

Answer:

A. 30 km

Solution: Given: A person walks a distance from point A to B at 15 km/h, and from point B to A at 30 km/h. He takes 3 hours to complete the journey, Concept used: Distance = velocity × time Velocity = distance/time Time = distance/velocity Calculation: Let the distance between A to B be x km According to the question, x/15 + x/30 = 3 ⇒ 3x/30 = 3 ⇒ x = 30 km ∴ The distance between A to B is 30 km. Shortcut TrickCalculation: Distance = {(S1 × S2)/(S1 + S2)} × total time Distance = {(15 × 30)/(15 + 30)} × 3 Distance = 30 km. ∴ The correct answer is 30 km.