Question

The speed of a boat in still water is 32km/hr and the speed of the current is 8km/hr. It takes a total of 15hours to row to upstream from Point A to B and downstream from Point B to C. If the distance between A to C is two-fifth the distance between B and C then what is the distance between B and C? (Where BC < AB)

A 180km Correct Answer Incorrect Answer
B 160km Correct Answer Incorrect Answer
C 80km Correct Answer Incorrect Answer
D 150km Correct Answer Incorrect Answer
E 140km Correct Answer Incorrect Answer

Solution

Let the distance from B to C be xkm ∴ A to C = 2x/5 km Upstream speed = 32 – 8 = 24 km/hr Downstream speed = 32 + 8 = 40km/hr Now,  7x/(5 × 24) + x/40 = 15  7x/120 + x/40 = 15 (7x + 3x)/120 = 15 x = 180 km

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