CMA Foundation · Fundamentals of Business Mathematics and Statistics · Time and Distance
A boat covers 30 km upstream in 5 hours. If the speed of the stream is 1.5 km/h, what is the speed of the boat in still water?
The upstream speed is 30 divided by 5, which is 6 km/h. Since upstream speed equals boat speed minus stream speed, the boat speed in still water is 6 plus 1.5, which equals 7.5 km/h.
- A4.5 km/h
- B6 km/h
- C7.5 km/hCorrect
- D9 km/h
Explanation
Upstream speed = 30/5 = 6 km/h. Still water speed = upstream speed + stream speed = 6 + 1.5 = 7.5 km/h. The 4.5 km/h option subtracts the stream speed, which is the wrong sign.
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