Multiple choice

A boat takes 6 hours to travel a certain distance against the stream and comes back to the starting point. If the speed of the boat in still water is 4 km/hr. What is the distance between the two points?

  1. 10 km

  2. 8 km

  3. 7 km

  4. 6 km

  5. Cannot be determined
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The round trip takes 6 hours: d/(4-s) + d/(4+s) = 6, where d is distance and s is stream speed. This is one equation with two unknowns, so multiple (d,s) pairs satisfy it. Without knowing stream speed, the distance cannot be uniquely determined.

Keep practicing — related questions