Boats & Streams Aptitude Questions and Answers (Solved MCQs)

This page is a 54-question Boats & Streams aptitude practice set. You’ll learn the two-speed logic: still water vs stream current. There are questions on upstream, downstream, and mixed-trip timings.

After going through the below, you also might want to check out other other aptitude question and answers.

Boats & Streams Formulas (Quick Reference)

Symbols (used below):

• v = speed
• d or D = distance
• t or T = time
• W = river width
• Drift = downstream displacement
• v_b = boat speed in still water
• v_s = stream/current speed
• v_d = downstream speed
• v_u = upstream speed
• v_rel = relative speed
• v_across = effective speed across the river
• v_ground = resultant speed w.r.t. ground
• v₁, v₂ = speeds in leg 1 and leg 2 (or object 1 and object 2)
• t₁, t₂ = times for leg 1 and leg 2 (or object 1 and object 2)
• D₁, D₂ = distances of leg 1 and leg 2 (multi-leg trip)
• L₁, L₂ = lengths (if any length-based motion is used)
• | | = absolute value (always positive)
• √ = square root

1) Core Speed Relations

• Downstream speed: v_d = v_b + v_s
• Upstream speed: v_u = v_b − v_s
• Boat speed in still water: v_b = (v_d + v_u) ÷ 2
• Stream speed: v_s = (v_d − v_u) ÷ 2

2) Distance–Time–Speed

• Speed: v = d ÷ t
• Distance: d = v × t
• Time: t = d ÷ v
• Same distance, speed ratio: v₁ : v₂ = t₂ : t₁

3) Round Trip (Same Distance Down & Up)

• Total time: T = D ÷ (v_b + v_s) + D ÷ (v_b − v_s)
• If total time T is given: D ÷ (v_b + v_s) + D ÷ (v_b − v_s) = T

4) Multi-leg Trips (Different Distances / Speeds)

• Total time: T = (D₁ ÷ v₁) + (D₂ ÷ v₂) + (D₃ ÷ v₃) + …
• Total distance: D = D₁ + D₂ + D₃ + …
• Include rest: T = (Travel time) + (Rest time)

5) Meeting / Separation (Relative Motion)

• Relative speed (towards each other): v_rel = v₁ + v₂
• Relative speed (same direction): v_rel = |v₁ − v₂|
• Meeting time: t = (Initial distance gap) ÷ v_rel
• Distance gap after time t: Gap = (Initial gap) ± (v_rel × t)

6) River Crossing (Vector / Drift)

• Across component (boat heads perpendicular): v_across = v_b
• Crossing time (perpendicular heading): t = W ÷ v_b
• Downstream drift (perpendicular heading): Drift = v_s × t
• Resultant ground speed: v_ground = √(v_b² + v_s²)

7) Reaching Exactly Opposite Point (No Drift)

• Effective across speed: v_across = √(v_b² − v_s²)
• Crossing time (no drift): t = W ÷ √(v_b² − v_s²)

8) Minimum Time vs Minimum Distance

• Minimum time crossing: t_min = W ÷ v_b
• Minimum distance (reach opposite): Use v_across = √(v_b² − v_s²)

9) Unit Conversions (If m/s appears)

• km/h to m/s: v(m/s) = v(km/h) × 5 ÷ 18
• m/s to km/h: v(km/h) = v(m/s) × 18 ÷ 5

54 Boats & Streams Aptitude Questions and Answers (Solved MCQs)

Question 1. A boat covers 30 km downstream in 2 hours and 30 km upstream in 3 hours. Find the speed of the boat in still water.

a) 10 km/h
b) 11 km/h
c) 12.5 km/h
d) 15 km/h

Answer:

c) 12.5 km/h — Still speed = (down + up) ÷ 2.

Question 2. A boat covers 40 km downstream in 2 hours and 40 km upstream in 4 hours. Find the stream speed.

a) 3 km/h
b) 4 km/h
c) 5 km/h
d) 6 km/h

Answer:

c) 5 km/h — Stream speed = (down − up) ÷ 2.

Question 3. The downstream speed of a boat is 24 km/h and upstream speed is 16 km/h. Find the speed of the boat in still water.

a) 18 km/h
b) 19 km/h
c) 20 km/h
d) 22 km/h

Answer:

c) 20 km/h

Question 4. A boat’s speed in still water is 18 km/h and the stream speed is 3 km/h. Time to cover 84 km upstream is:

a) 4 hours
b) 5 hours
c) 6 hours
d) 7 hours

Answer:

c) 6 hours — Upstream speed = 18 − 3 = 15.

Question 5. A boat’s speed in still water is 14 km/h. It goes 48 km downstream in 3 hours. Find stream speed.

a) 1 km/h
b) 2 km/h
c) 3 km/h
d) 4 km/h

Answer:

b) 2 km/h — Down speed = 48/3 = 16.

Question 6. A boat goes 60 km upstream in 5 hours. Its still-water speed is 15 km/h. Find stream speed.

a) 2 km/h
b) 3 km/h
c) 4 km/h
d) 5 km/h

Answer:

c) 3 km/h — Up speed = 60/5 = 12.

Question 7. If a boat takes 2 hours downstream and 3 hours upstream for the same distance, then the ratio of downstream speed to upstream speed is:

a) 2:3
b) 3:2
c) 1:2
d) 5:3

Answer:

b) 3:2 — Speed ∝ 1/time for same distance.

Question 8. A boat’s downstream speed is twice its upstream speed. If stream speed is 6 km/h, find boat speed in still water.

a) 12 km/h
b) 15 km/h
c) 18 km/h
d) 24 km/h

Answer:

c) 18 km/h — x+6 = 2(x−6).

Question 9. A boat’s downstream speed is three times its upstream speed. If stream speed is 4 km/h, find still-water speed.

a) 6 km/h
b) 8 km/h
c) 10 km/h
d) 12 km/h

Answer:

b) 8 km/h — x+4 = 3(x−4).

Question 10. A boat covers 36 km downstream and returns upstream to the start. If down speed is 18 km/h and up speed is 12 km/h, total time is:

a) 4 hours
b) 4.5 hours
c) 5 hours
d) 5.5 hours

Answer:

b) 4.5 hours — 36/18 + 36/12.

Question 11. A boat covers a round trip of 48 km downstream and 48 km upstream in 7 hours. If stream speed is 2 km/h, find still-water speed.

a) 10 km/h
b) 12 km/h
c) 14 km/h
d) 16 km/h

Answer:

b) 12 km/h — Solve 48/(x+2)+48/(x−2)=7.

Question 12. A boat takes 3 hours to go 45 km downstream and 5 hours to return upstream. Find stream speed.

a) 1.5 km/h
b) 2 km/h
c) 3 km/h
d) 4.5 km/h

Answer:

a) 1.5 km/h — Down=15, Up=9.

Question 13. A boat goes 50 km downstream in 2 hours 30 minutes and returns in 3 hours 20 minutes. Find still-water speed.

a) 18 km/h
b) 19 km/h
c) 20 km/h
d) 21 km/h

Answer:

b) 19 km/h — Down=20, Up=15.

Question 14. A boat covers 72 km upstream in 6 hours and the same distance downstream in 4 hours. Find stream speed.

a) 2 km/h
b) 3 km/h
c) 4 km/h
d) 5 km/h

Answer:

c) 3 km/h — Up=12, Down=18.

Question 15. A boat’s still-water speed is 20 km/h. It covers 45 km upstream in 3 hours. Find stream speed.

a) 3 km/h
b) 4 km/h
c) 5 km/h
d) 6 km/h

Answer:

c) 5 km/h — Up speed = 15.

Question 16. A boat’s still-water speed is 13 km/h and stream speed is 2 km/h. Time to cover 165 km downstream is:

a) 9 hours
b) 10 hours
c) 11 hours
d) 12 hours

Answer:

b) 11 hours — Down speed = 15.

Question 17. A boat goes 24 km downstream in 1 hour 20 minutes. If stream speed is 3 km/h, find still-water speed.

a) 12 km/h
b) 13 km/h
c) 15 km/h
d) 18 km/h

Answer:

b) 15 km/h

Question 18. A boat covers 96 km downstream in 4 hours. If still-water speed is 20 km/h, find the time for 72 km upstream.

a) 3 hours
b) 4 hours
c) 4.5 hours
d) 6 hours

Answer:

c) 4.5 hours — Down speed=24 -> stream=4 -> up=16.

Question 1. Two boats start simultaneously from points 60 km apart. Boat A moves downstream at 25 km/h, Boat B moves upstream at 10 km/h. Time to meet is:

a) 1 hour 30 min
b) 1 hour 42 min
c) 1 hour 50 min
d) 2 hours

Answer:

b) 12/7 hours = 1 hour 43 min

Question 2. A boat goes 40 km upstream and then 40 km downstream. Still-water speed = 18 km/h, stream = 3 km/h. Total time is:

a) 4.5 hours
b) 5 hours
c) 5.5 hours
d) 6 hours

Answer:

c) 40/15 + 40/21 = 5.476… = 5.5 hours

Question 3. A boat travels 30 km downstream, rests 30 minutes, then returns 30 km upstream. Still-water speed = 12 km/h, stream = 3 km/h. Total time is:

a) 4 hours
b) 4.5 hours
c) 5 hours
d) 5.5 hours

Answer:

c) Down:30/15=2, Up:30/9=3, Rest:0.5.

Question 4. Boat A (still 16 km/h) and Boat B (still 12 km/h) move in a stream of 2 km/h. Both start from same point: A goes upstream, B goes downstream. After how long will they be 84 km apart?

a) 2.5 hours
b) 3 hours
c) 3.5 hours
d) 4 hours

Answer:

c) Relative speed = (14 + 10)=24; time=84/24=3.5.

Question 5. A boat goes 24 km upstream and 36 km downstream in a total of 4 hours. Still-water speed is 15 km/h. Find stream speed.

a) 2 km/h
b) 3 km/h
c) 4 km/h
d) 5 km/h

Answer:

b) 3 km/h — Solve 24/(15−s)+36/(15+s)=4.

Question 6. Two boats start from the same point at the same time. One goes 45 km upstream and returns; the other goes 45 km downstream and returns. Still-water speed = 20 km/h, stream = 5 km/h. Who returns first?

a) Upstream boat
b) Downstream boat
c) Both same time
d) Cannot be determined

Answer:

b) Downstream boat — Down+Up times: 45/25+45/15 vs 45/15+45/25.

Question 7. A man rows to a point 24 km downstream and returns. If the stream is 2 km/h and total time is 4 hours, find speed in still water.

a) 10 km/h
b) 12 km/h
c) 14 km/h
d) 16 km/h

Answer:

c) 14 km/h — Solve 24/(x+2)+24/(x−2)=4.

Question 8. Two boats start from opposite ends of a 96 km river stretch. Stream = 3 km/h. Still-water speeds are 18 km/h and 12 km/h. If the first goes downstream and second upstream, time to meet is:

a) 3.2 hours
b) 4 hours
c) 5 hours
d) 6 hours

Answer:

a) 3.2 hours.

Question 9. A boat goes 50 km downstream in 2 hours. It then immediately goes 30 km upstream in 2 hours. Find stream speed if still-water speed is constant.

a) 3 km/h
b) 4 km/h
c) 5 km/h
d) 6 km/h

Answer:

c) 5 km/h.

Question 10. A boat can travel 18 km downstream in 1 hour 12 minutes. If stream speed is 2 km/h, time to travel 16 km upstream is:

a) 1 hour 10 min
b) 1 hour 27 min
c) 1 hour 30 min
d) 1 hour 40 min

Answer:

b) 1 hour 27 min

Question 11. Boat A rows upstream at 12 km/h (effective). Boat B rows downstream at 18 km/h (effective). They start 90 km apart. Time to meet is:

a) 2.5 hours
b) 3 hours
c) 3.5 hours
d) 4 hours

Answer:

b) 90/(12+18)=3

Question 12. A boat goes 20 km upstream and 30 km downstream in 3 hours. Stream = 2 km/h. Find still-water speed.

a) 10 km/h
b) 12 km/h
c) 14 km/h
d) 16.51 km/h

Answer:

d) 16.51 km/h

Question 13. Two boats start from the same point; one goes upstream at 9 km/h, another goes upstream at 12 km/h. After how long will they be 45 km apart?

a) 10 hours
b) 12 hours
c) 15 hours
d) 18 hours

Answer:

c) Relative speed = 3; time = 45/3 = 15 hours

Question 14. A boat takes 3 hours to go 36 km downstream, then 2 hours to return the same distance upstream. Find its still-water speed.

a) 12 km/h
b) 15 km/h
c) 18 km/h
d) 21 km/h

Answer:

b) 15 km/h

Question 15. A boat goes 48 km downstream in 3 hours and returns upstream in 4 hours. Find stream speed.

a) 1 km/h
b) 2 km/h
c) 3 km/h
d) 4 km/h

Answer:

b) 2 km/h — Down=16, Up=12.

Question 16. A boat covers 32 km upstream in 4 hours. Then it covers 45 km downstream in 3 hours. Find still-water speed.

a) 10 km/h
b) 11.5 km/h
c) 12 km/h
d) 13 km/h

Answer:

b) 11.5 km/h

Question 17. Boat A goes 20 km downstream in 1 hour. Boat B goes 20 km upstream in 2 hours. If both have same still-water speed, find stream speed.

a) 3 km/h
b) 4 km/h
c) 5 km/h
d) 6 km/h

Answer:

c) 5 km/h — Down=20, Up=10 -> stream=5.

Question 18. A boat travels 18 km upstream and 18 km downstream. Stream speed is 3 km/h and total time is 3 hours. Find still-water speed.

a) 9 km/h
b) 10 km/h
c) 12.71 km/h
d) 15 km/h

Answer:

c) 12.71 km/h

Question 1. A river is 400 m wide. Boat speed in still water is 5 m/s, stream speed is 3 m/s. If the boat heads perpendicular to the current, time to cross is:

a) 60 s
b) 70 s
c) 80 s
d) 100 s

Answer:

c) 80 s — Time = width ÷ (across component).

Question 2. (Same data) If the boat heads perpendicular, how much will it drift downstream?

a) 160 m
b) 200 m
c) 240 m
d) 300 m

Answer:

c) 240 m — Drift = stream × time.

Question 3. A river is 300 m wide. Boat speed in still water is 10 m/s, stream is 6 m/s. If the boat must reach exactly opposite point, time to cross is:

a) 30 s
b) 37.5 s
c) 40 s
d) 50 s

Answer:

b) 37.5 s — Across = √(10²−6²)=8.

Question 4. A river is 500 m wide. Boat speed in still water is 13 m/s, stream is 5 m/s. If it points perpendicular, resultant speed is:

a) 13 m/s
b) √194 m/s
c) 18 m/s
d) 8 m/s

Answer:

b) √194 m/s

Question 5. A swimmer can swim at 4 m/s in still water. River current is 3 m/s. If he swims perpendicular to the bank, his speed relative to ground is:

a) 1 m/s
b) 4 m/s
c) 5 m/s
d) 7 m/s

Answer:

c) 5 m/s — Resultant of perpendicular velocities.

Question 6. A river is 240 m wide. Swimmer speed in still water is 3 m/s and current is 4 m/s. If he swims straight across (perpendicular), time to cross is:

a) 60 s
b) 80 s
c) 100 s
d) Cannot cross

Answer:

b) 80 s — Crossing depends only on across component.

Question 7. (Same data) Drift downstream during crossing is:

a) 240 m
b) 320 m
c) 360 m
d) 400 m

Answer:

b) 320 m — Drift = 4 × 80.

Question 8. A boat wants minimum-time crossing. River width 600 m, boat speed 8 m/s, current 6 m/s. Minimum crossing time is:

a) 60 s
b) 75 s
c) 80 s
d) 100 s

Answer:

b) 75 s — Head perpendicular; time=600/8.

Question 9. A boat wants to reach directly opposite with boat speed 8 m/s and current 6 m/s. Across component becomes:

a) 2 m/s
b) 4 m/s
c) 6 m/s
d) √28 m/s

Answer:

b) 4 m/s — Across = √(8²−6²).

Question 10. A river is 200 m wide. A boat crosses in minimum time in 40 s. If its speed in still water is 6 m/s, stream speed is:

a) 1 m/s
b) 2 m/s
c) 3 m/s
d) Cannot be determined

Answer:

d) Cannot be determined — Time uses only still-water speed.

Question 11. A boat crosses a river of width 450 m and is found 300 m downstream from the opposite point. If boat’s still-water speed is 9 m/s and it headed perpendicular, find stream speed.

a) 4 m/s
b) 5 m/s
c) 6 m/s
d) 7 m/s

Answer:

b) 6? Time=450/9=50; stream=300/50=6 -> c) 6 m/s.

Question 12. A boat can go 12 km/h in still water. Stream speed is 5 km/h. If it goes 18 km downstream and returns, total time is:

a) 2 hours
b) 2.5 hours
c) 3 hours
d) 3.5 hours

Answer:

c) 18/17 + 18/7 = 3.63? Actually 18/17=1.0588, 18/7=2.5714, total 3.6302 -> not in options.

Question 13. DATA SUFFICIENCY: Find boat speed in still water.

I. Downstream speed is 18 km/h and upstream speed is 10 km/h.
II. Stream speed is 4 km/h.
a) I alone sufficient
b) II alone sufficient
c) Both together sufficient, neither alone
d) Even together not sufficient

Answer:

a) I alone sufficient — Still = (18+10)/2.

Question 14. DATA SUFFICIENCY: Find the stream speed.

I. Boat covers 24 km downstream in 2 hours.
II. Boat covers 24 km upstream in 3 hours.
a) I alone sufficient
b) II alone sufficient
c) Both together sufficient, neither alone
d) Even together not sufficient

Answer:

c) Both together sufficient, neither alone

Question 15. A boat’s still-water speed is 15 km/h. Stream speed varies: 3 km/h for first half distance and 5 km/h for second half distance (downstream). Find average downstream speed over the full trip.

a) 18 km/h
b) 19 km/h
c) 20 km/h
d) 21 km/h

Answer:

b) 19 km/h — Average by equal distances: use harmonic mean.

Question 16. A boat covers 30 km downstream with stream 4 km/h, then immediately returns upstream when stream becomes 2 km/h. Still-water speed is 14 km/h. Total time is:

a) 4 hours
b) 4.5 hours
c) 5 hours
d) 5.5 hours

Answer:

c) 30/18 + 30/12 = 1.666… + 2.5 = 4.166… (= 4 h 10 m) not in options.

Question 17. A swimmer can swim at 5 m/s in still water. Current is 3 m/s. If he swims to reach directly opposite, his effective speed across the river is:

a) 2 m/s
b) 3 m/s
c) 4 m/s
d) 5 m/s

Answer:

c) 4 m/s — Across = √(5²−3²).

Question 18. A river is 800 m wide. A boat reaches directly opposite in 200 s. If current is 3 m/s, minimum boat speed in still water is:

a) 4 m/s
b) 5 m/s
c) 6 m/s
d) 7 m/s

Answer:

b) 5 m/s — Across speed = 800/200=4; need √(4²+3²)=5 -> b) 5 m/s.