Explanation:
New speed = 5/6 of normal pace => New time = 6/5 of normal time. Difference = 1/5 of normal time = 10 minutes. Normal time = 10 * 5 = 50 minutes.
A motorboat covers a certain distance downstream in a river in 3 hours and returns upstream in 4 hours. If the speed of the river current is 3 km/h, find the speed of the motorboat in still water.
Explanation:
Let speed of boat in still water be v. Downstream speed = v + 3, Upstream speed = v - 3. Distance is same, so 3(v + 3) = 4(v - 3) => 3v + 9 = 4v - 12 => v = 21 km/h.
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