Question
A boat travels 48 km downstream in 4 hours and 24 km
upstream in 6 hours. What is the speed of the boat in still water?Solution
Let the speed of the boat in still water be B km/h and the speed of the stream be S km/h. Downstream speed = B + S, and upstream speed = B - S. Downstream, distance = 48 km, time = 4 hours: B + S = 48 / 4 = 12 km/h. Upstream, distance = 24 km, time = 6 hours: B - S = 24 / 6 = 4 km/h. Now, solve the two equations: B + S = 12 B - S = 4 Add the two equations: 2B = 16 B = 8 km/h So, the speed of the boat in still water is 8 km/h. Correct Option: a) 8 km/h
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