Multiple choice

The speed of boat when travelling downstream is 32 km/h, whereas when travelling upstream it is 28 km/h. What is the speed of the boat in still water?

  1. 28

  2. 32

  3. 30

  4. 34

  5. 35
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Speed of boat in still water = (downstream speed + upstream speed)/2. This is because downstream speed = boat speed + stream speed, and upstream speed = boat speed - stream speed. Adding them cancels out the stream speed. Therefore, still water speed = (32+28)/2 = 30 km/h.

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