Question
If a boat travels 18 km more in downstream than in
upstream in 3 hours and if the speed of the Boat in still water is 20 kmph. Find the distance travelled by boat in downstream in 4 hours?Solution
Difference in travelling distance in downstream and upstream in 1 hour is 6 km  Let the speed of upstream be x km/hr  Speed of downstream = x + 6 km/hr  speed of the Boat in still water = 20 km/hr  1/2 x (x + x + 6) = 20  2x + 6 = 40  x = 17 km/hr  Speed of downstream = 17 + 6 = 23 km/hr  Distance travelled in 4 hours = 23 x 4 = 92 km
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