Practice Quantitative Aptitude questions on Boats and Streams, covering upstream and downstream speeds, speed of a boat in still water, speed of the stream, and calculations involving time, distance, and relative speed. Takes approximately 20–25 minutes and is useful for placement tests, TCS NQT, SSC, banking and MBA entrance exams.
Question 1
What will be the boat's speed in still water and speed of river, if the boat takes 12 hours to row 48 km upstream and 8 hours to row the same distance downstream?
Explanation
Upstream speed = 4812 = 4 km/hr and downstream speed = 488 = 6 km/hr.
Speed of the boat = 6 + 42 = 5 km/hr and speed of the river = 6 - 42 = 1 km/hr.
Speed of the boat = 6 + 42 = 5 km/hr and speed of the river = 6 - 42 = 1 km/hr.
Question 2
Find the ratio of swimming speed of Raj in still water to speed of river, if ratio of time taken to go 10km upstream to time taken to go 10km downstream is 11:5?
Explanation
Let the speed in still water be b and the river's speed be s. The time is inversely proportional to the speed.
b + sb - s = 115, so 5b + 5s = 11b - 11s and 6b = 16s.
b : s = 16 : 6 = 8 : 3.
b + sb - s = 115, so 5b + 5s = 11b - 11s and 6b = 16s.
b : s = 16 : 6 = 8 : 3.
Question 3
Michel can swim in still water at the rate of 6km per hour. After swimming in a stream, she realized that she takes twice the time to go upstream as she takes to go downstream. What is speed of the current?
Explanation
Let the speed of the current be s. Her upstream speed = 6 - s and downstream speed = 6 + s. The time upstream is twice the time downstream, so the upstream speed is half the downstream speed.
6 - s = 6 + s2, so 12 - 2s = 6 + s and s = 2 km/hr.
6 - s = 6 + s2, so 12 - 2s = 6 + s and s = 2 km/hr.
Question 4
Raj swims 26 km downstream in same time as 14 km upstream. What is his speed in still water if speed of stream is 3 km/hr?
Explanation
Let the speed in still water be v. The times are equal, so 26v + 3 = 14v - 3.
26v - 78 = 14v + 42, so 12v = 120 and v = 10 km/hr.
26v - 78 = 14v + 42, so 12v = 120 and v = 10 km/hr.
Question 5
Consider statements A and B given below and decide whether they are enough to find the time needed for covering same distance downstream as upstream if a boat travels 48 kms upstream in 6 hours.
Statement A – Boat’s speed in still water is 10 km/hr
Statement B – Current speed is 2 km/hr
Statement A – Boat’s speed in still water is 10 km/hr
Statement B – Current speed is 2 km/hr
Explanation
The upstream speed = 486 = 8 km/hr. The downstream speed = the upstream speed + 2 × the current speed.
Statement B alone gives the current speed = 2, so the downstream speed = 12 and the time = 4812 = 4 hours.
Statement A alone gives the current = 10 - 8 = 2 km/hr, which also leads to the answer.
So any one statement is enough.
Statement B alone gives the current speed = 2, so the downstream speed = 12 and the time = 4812 = 4 hours.
Statement A alone gives the current = 10 - 8 = 2 km/hr, which also leads to the answer.
So any one statement is enough.
Question 6
3 towns P, Q and R are located at the bank of a stream. Distance of Q from P and R is same. Jeet rows from P to Q and Q to P in total 10 hours. Jeet also requires 4 hours to row from P to R. If the stream flows at a consistent rate what will be the ratio of Jeet’s speed in still water and speed of stream?
Explanation
Let the boat's speed in still water be b and the stream's speed be s. Q is midway between P and R, and PQ = QR = d.
P to Q and back takes 10 hours: db + s + db - s = 10. P to R (2d, downstream) takes 4 hours: 2db + s = 4, so db + s = 2.
Then db - s = 8, so b + sb - s = 4, which gives 5s = 3b.
b : s = 5 : 3.
P to Q and back takes 10 hours: db + s + db - s = 10. P to R (2d, downstream) takes 4 hours: 2db + s = 4, so db + s = 2.
Then db - s = 8, so b + sb - s = 4, which gives 5s = 3b.
b : s = 5 : 3.
Question 7
Raj swims for 6 ½ hours while going 24 km downstream and 36 km upstream. But he takes just 6 hours to swim 36 km downstream and 24 km upstream. At what rate is the river flowing?
Explanation
Let the boat's speed be b and the river's speed be r. Let u = 1b + r and v = 1b - r.
24u + 36v = 6.5 and 36u + 24v = 6.
Multiply the first by 3 and the second by 2: 72u + 108v = 19.5 and 72u + 48v = 12, so 60v = 7.5 and v = 18, so b - r = 8.
Then 24u = 6.5 - 36 × 18 = 2, so u = 112 and b + r = 12.
b = 10 and r = 2 km/hr.
24u + 36v = 6.5 and 36u + 24v = 6.
Multiply the first by 3 and the second by 2: 72u + 108v = 19.5 and 72u + 48v = 12, so 60v = 7.5 and v = 18, so b - r = 8.
Then 24u = 6.5 - 36 × 18 = 2, so u = 112 and b + r = 12.
b = 10 and r = 2 km/hr.
Question 8
An ocean current flows at a rate of 1.5 km/hr. A shark can swim in still water at the rate 4.5 km/hr. What is the average speed for the entire distance travelled, if the shark swims from India to Australia and comes back?
Explanation
The speed with the current = 4.5 + 1.5 = 6 km/hr and against it = 4.5 - 1.5 = 3 km/hr.
For the same distance both ways, the average speed = 2 × 6 × 36 + 3 = 369 = 4 km/hr.
For the same distance both ways, the average speed = 2 × 6 × 36 + 3 = 369 = 4 km/hr.
Question 9
It takes P 1 hour to row to a place and to come back. If the river is running at 2.4 km/hr and P has a speed of 12 km/hr in still water, what distance is the place from P’s starting point?
Explanation
The speed downstream = 12 + 2.4 = 14.4 km/hr and upstream = 12 - 2.4 = 9.6 km/hr.
d14.4 + d9.6 = 1, so d × 2 + 328.8 = 1, that is d × 528.8 = 1.
d = 28.85 = 5.76 km.
d14.4 + d9.6 = 1, so d × 2 + 328.8 = 1, that is d × 528.8 = 1.
d = 28.85 = 5.76 km.
Question 10
A boat running downstream covers a distance of 20 km in 2 hours while for covering the same distance upstream, it takes 5 hours. What is the speed of the boat in still water?
Explanation
Speed downstream = 202 = 10 km/hr and speed upstream = 205 = 4 km/hr.
Speed of the boat in still water = 10 + 42 = 7 km/hr.
Speed of the boat in still water = 10 + 42 = 7 km/hr.
Question 11
If a boat is rowed downstream for 50 km in 5 hours and upstream for 24 km in 6 hours, what is the speed of the boat and the river?
Explanation
Speed downstream = 505 = 10 km/hr and speed upstream = 246 = 4 km/hr.
Speed of the boat = 10 + 42 = 7 km/hr and speed of the river = 10 - 42 = 3 km/hr.
Speed of the boat = 10 + 42 = 7 km/hr and speed of the river = 10 - 42 = 3 km/hr.
Question 12
A boatman rows 96 km downstream in 8 hours with a stream speed of 4kmph. How much time will he take to cover 8km upstream?
Explanation
Speed downstream = 968 = 12 kmph. The stream speed is 4 kmph, so the speed of the boat in still water = 12 - 4 = 8 kmph.
Speed upstream = 8 - 4 = 4 kmph.
Time for 8 km upstream = 84 = 2 hours.
Speed upstream = 8 - 4 = 4 kmph.
Time for 8 km upstream = 84 = 2 hours.
Question 13
A boat has a speed of 14kmph in standing water. The stream has a speed of 1.2kmph. What time does the boat take to go to a distance of 4864 km and come back? (hours)
Explanation
Speed downstream = 14 + 1.2 = 15.2 kmph and speed upstream = 14 - 1.2 = 12.8 kmph.
Time = 486415.2 + 486412.8 = 320 + 380 = 700 hours.
Time = 486415.2 + 486412.8 = 320 + 380 = 700 hours.
Question 14
A man rows d km upstream and back again downstream to the same point in T hours. The speed of rowing in still water is x km/hr and the rate of stream is y km/hr. Then
Explanation
The speed upstream = x - y and the speed downstream = x + y.
Total time T = dx - y + dx + y = d(x + y + x - y)x² - y² = 2xdx² - y².
So x² - y² = 2xdT.
Total time T = dx - y + dx + y = d(x + y + x - y)x² - y² = 2xdx² - y².
So x² - y² = 2xdT.
Question 15
A boat travels 26 km downstream and 14 km upstream in the same time. Its speed in still water is 10 kmph. Find the speed of the stream.
Explanation
Let stream=s. 26/(10+s)=14/(10-s). Solving: 260-26s=140+14s, giving 40s=120, so s=3.
Question 16
The speed of a boat with the current is 15 km/hr. The speed of the current is 2.5 kmph. What is the boat's speed against the current?
Explanation
Still-water speed = 15-2.5=12.5. Against current = 12.5-2.5 = 10 kmph.
Question 17
The speed of a boat in still water is 5 kmph. The velocity of current is 1 kmph. If it takes him 1 hr to row to a place and come back, how far is the place?
Explanation
Downstream=6 km/h, upstream=4 km/h. Let distance=d. d/6+d/4=1, giving 5d/12=1, so d=2.4 km.
Question 18
A boat covers 24 km in 6 hours moving upstream. It also covers 24 km in 3 hours moving downstream. Find the speed of the stream.
Explanation
Upstream speed = 246 = 4 km/hr. Downstream speed = 243 = 8 km/hr. Speed of stream = (8-4)/2 = 2 km/hr.
Question 19
A boat running downstream covers a distance of 30 km in 2 hours while for covering the same distance upstream, it takes 5 hours. What is the speed of the boat in still water?
Explanation
Downstream speed = 302 = 15 km/hr. Upstream speed = 305 = 6 km/hr. Still-water speed = (15+6)/2 = 10.5 km/hr.
Question 20
A man rows downstream 36 km and 18 km upstream. If he takes 9 hours to cover each distance, then the velocity (in kmph) of the current is
Explanation
Downstream speed = 369 = 4 km/hr. Upstream speed = 189 = 2 km/hr. Current = (4-2)/2 = 1 km/hr.
Question 21
A man can row upstream at 20 km/hr and downstream at 25 km/hr. Find man's rate in still water.
Explanation
Rate in still water = (20+25)/2 = 22.5 km/hr.
Question 22
A man's speed in the direction of the current is 20 km/hr and the speed of the current itself is 5 km/hr. The man's speed against the current would be
Explanation
Still water speed = 20 - 5 = 15 km/hr. Speed against current = 15 - 5 = 10 km/hr.
Question 23
In 1 hour, a boat goes 12 km/hr along the stream and 6 km/hr against the stream. The speed of the boat in still water (in km/hr) is
Explanation
Speed in still water = (downstream + upstream)/2 = (12+6)/2 = 9 km/hr.
Question 24
A boat running downstream covers a distance of 30 km in 5 hours while for covering the same distance upstream, it takes 6 hours. What is the speed of the boat in still water?
Explanation
Downstream speed = 305 = 6 km/hr. Upstream speed = 306 = 5 km/hr. Still-water speed = (6+5)/2 = 5.5 km/hr.
Question 25
A man can row upstream at 9 km/h and downstream at 20 km/h. Find man's rate in still water and the rate of current.
Explanation
Rate in still water = (20+9)/2 = 14.5 km/hr. Rate of current = (20-9)/2 = 5.5 km/hr. Neither value matches any listed option pair, so the answer is None.
