A boat's speed in still water is 15 km/h and the stream flows at 5 km/h. How long does it take to go 24 km downstream and return?
Answer and explanation
Correct answer: D. 3.6 hours
- Step 1: Downstream speed = 15 + 5 = 20 km/h; upstream speed = 15 - 5 = 10 km/h.
- Step 2: Time = 24/20 + 24/10 = 3.6 hours.
Answer
3.6 hours.
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