- A30 minutes
- B15 minutes
- C7.5 minutes
- D60 minutes
Step-by-Step Solution
Upstream = 4 ÷ (2/3) = 6 km/h; downstream = 4 ÷ 0.4 = 10 km/h. Current = 2 km/h, so 1 km takes 1/2 h = 30 minutes.
Answer: A) 30 minutes
A rower takes 40 minutes for 4 km against the current and 24 minutes for 4 km with it. How many minutes would a floating leaf need to drift 1 km?
Competition practiceBoats & Streams
Master this topic in 30 minutes a day.
Don't just memorise the answer — build a daily practice habit.
Practice 5 Similar Questions Free →All Boats & Streams practice questions
More Boats & Streams practice
A police boat (16 km/h in still water) heads upstream and a ferry (12 km/h in still…Launch X (13 km/h in still water) leaves Patna ghat going upstream. Thirty minutes later…In the figure, the boat leaves A at 7 a.m., reaches B, waits there for 30 minutes, then…A steamer's still-water speed is 25 km/h. It goes 90 km upstream in 4.5 hours. How long…A motorboat goes 30 km downstream and comes back in a total of 4.5 hours. The stream…