Multiple choice

The upstream speed of the boat is 40 km/hr and the speed of the boat in still water is 55 km/hr. What is the downstream speed of the boat?

  1. 75 km/hr

  2. 70 km/hr

  3. 60 km/hr

  4. 65 km/hr

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Upstream speed = Boat - Stream = 40. Still water = Boat = 55. Stream = 55 - 40 = 15 km/hr. Downstream speed = Boat + Stream = 55 + 15 = 70 km/hr.

AI explanation

The downstream speed equals the speed in still water plus the stream speed, while the upstream speed equals the still water speed minus the stream speed. Since the upstream speed is 40 km/hr and the still water speed is 55 km/hr, the stream speed is 55 - 40 = 15 km/hr. Adding this stream speed back to the still water speed gives a downstream speed of 55 + 15 = 70 km/hr. The result is 70 km/hr.

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