Multiple choice

The speed of motor boat in still water is 40 km/h.Boat covers 120 km in downstream in 2 hours. In howmuch time the same distance will be cover by motorboat in upstream?

  1. 4 hours

  2. 7 hours

  3. 6 hours

  4. 5 hours

  5. 8 hours
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The downstream speed is 120/2 = 60 km/h. Since the still-water speed is 40 km/h, the stream speed is 20 km/h, making the upstream speed 20 km/h and the time 120/20 = 6 hours.

AI explanation

The downstream speed is the distance of 120 km divided by the time of 2 hours, which is 60 km/h. Using the downstream speed formula, the speed of the current is 60 km/h minus the still water speed of 40 km/h, resulting in 20 km/h. The upstream speed is 40 km/h minus 20 km/h, equaling 20 km/h, so the time to cover 120 km upstream is 120 divided by 20, which is 6 hours.

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