Multiple choice

A boat can cover 32 km upstream in 4 hours. Ratio of the speed of boat in still water to the speed of current is 5 : 1. In how much time can the boat cover 60 km downstream?

  1. 6 hours

  2. 5 hours

  3. 5.5 hours

  4. 7 hours

  5. 4 hours
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Upstream speed = 32/4 = 8 km/h. Let boat speed be 5x and current be 1x. Upstream speed = 5x - 1x = 4x. So 4x = 8, x = 2. Boat speed = 10, current = 2. Downstream speed = 10 + 2 = 12 km/h. Time for 60 km = 60/12 = 5 hours.

AI explanation

The boat's upstream speed is 32 km divided by 4 hours, which equals 8 km/h, and using the given ratio, the boat's speed in still water is 10 km/h while the speed of the current is 2 km/h. Adding these two speeds together using the downstream speed formula gives a downstream speed of 12 km/h. The time to cover 60 km downstream is 60 divided by 12, which is 5 hours.

Keep practicing — related questions