Boats and Streams Practice Questions

5 questions per page • Detailed step-by-step solutions

Question 11
Easy
If downstream speed of a boat is 16 kmph and its upstream speed is 11 kmph, what is the speed of stream?
A 1.5 kmph
B 2 kmph
C 3 kmph
D 2.5 kmph
Correct Answer: D

Explanation:

Speed of stream = (Downstream speed - Upstream speed) / 2 = (16 - 11) / 2 = 2.5 kmph.
Question 12
Easy
The time taken by a man to row his boat upstream is 3 times the time taken by the man to row the same distance in downstream. If the speed of the boat is 24 kmph, find the speed of the stream.
A 12 kmph
B 14 kmph
C 6 kmph
D 8 kmph
Correct Answer: A

Explanation:

Downstream speed / Upstream speed = 3 / 1 => (24 + v) / (24 - v) = 3 => 4v = 48 => v = 12 kmph.
Question 13
Easy
If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 3 kmph then the speed of the boat in still water is:
A 4.2 km/hr
B 9 km/hr
C 13 km/hr
D 21 km/hr
Correct Answer: C

Explanation:

Upstream speed = 7 / (42/60) = 7 / 0.7 = 10 kmph. Boat speed in still water = Upstream speed + Stream speed = 10 + 3 = 13 km/hr.
Question 14
Easy
A boat takes equal time to travel a distance of 81 km in upstream and 99 km in downstream. If the speed of the boat in still water is 20 km/h, then what is the speed of the current (in km/h)?
A 3 km/h
B 4 km/h
C 2 km/h
D 2.5 km/h
Correct Answer: C

Explanation:

Time is equal: 81 / (20 - v) = 99 / (20 + v) => 9(20 + v) = 11(20 - v) => 20v = 40 => v = 2 km/h.
Question 15
Easy
A boat goes a certain distance in downstream in 8 hour and return back in 12 hour. If speed of stream is 5 km/hr then find speed of boat?
A 33 km/hr
B 25 km/hr
C 63 km/hr
D 45 km/hr
Correct Answer: B

Explanation:

Distance is constant: 8 * (u + 5) = 12 * (u - 5) => 2(u + 5) = 3(u - 5) => 2u + 10 = 3u - 15 => u = 25 km/hr.