Multiple choice

The speed of a boat along the current and against the current is 24 km/hr and 11 km/hr respectively. What is the speed of a boat (in km/hr) in still water?

  1. 17.5

  2. 18.6

  3. 20.4

  4. 21.3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Speed downstream = boat + current = 24 km/hr. Speed upstream = boat - current = 11 km/hr. Adding: 2 × boat speed = 35, so boat speed = 17.5 km/hr. This is the average of downstream and upstream speeds. Option B would require the current to be 3.3 km/hr, which doesn't match.

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