Multiple choice

If a boat is moving upstream at a speed of 8 km/hr and goes downstream at a speed of 12 km/hr, then what is the speed of the stream?

  1. 9 km/h

  2. 6 km/hr

  3. 3 km/hr

  4. 2 km/hr

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Speed of boat (b) + speed of stream (s) = 12. Speed of boat (b) - speed of stream (s) = 8. Subtracting the equations: 2s = 4, so s = 2.

AI explanation

The formula for the speed of the stream is half the difference of the downstream speed and the upstream speed. Applying the given values gives 1/2 times 12 minus 8, resulting in 2 km/hr.