Question
A boat moves at 40 km/hr downstream and 10 km/hr
upstream. How long will it take to cover 150 km in still water?Solution
ATQ,
Let the boat’s speed in still water be x km/hr, and current speed be y km/hr. Then: Downstream speed = x + y = 40 ......(1) Upstream speed = x - y = 10 ......(2) Adding (1) and (2): x + y + x - y = 40 + 10 → 2x = 50 → x = 25 km/hr Time to travel 150 km in still water = 150 / 25 = 6 hours
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