Multiple choice

A boat goes downstream at the rate of 18 kmph and upstream at the rate of 12 kmph. Find the speed of the boat.

  1. 10 kmph

  2. 12 kmph

  3. 15 kmph

  4. 18 kmph

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

Downstream speed = boat speed + stream speed = 18 kmph. Upstream speed = boat speed - stream speed = 12 kmph. Adding these two equations: 2 × boat speed = 30, so boat speed = 15 kmph. The stream speed is 3 kmph (18 - 15 = 15 - 12 = 3). Option C (15 kmph) is correct.

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