Question
Ratio of speed of boat in downstream and speed of stream
is 7:3, if speed of current is 9 km/hr, then find distance travelled (in km) upstream in 6 hours.Solution
Given ratio: Downstream speed : Stream speed = 7:3 Stream speed = 9 km/hr Find downstream speed: Let Downstream speed = 7x and Stream speed = 3x Since 3x = 9 → x = 3 So, Downstream speed = 7×3=21 km/hr Find boat’s actual speed: Boat speed in still water = Downstream speed - Stream speed = 21 - 9 = 12 km/hr Find upstream speed: Upstream speed = Boat speed - Stream speed = 12 - 9 = 3 km/hr Find distance traveled upstream in 6 hours: Distance = Speed × Time = 3 × 6 = 18 km
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