All Exams  >   SSC CGL  >   Quantitative Aptitude for SSC CGL  >   All Questions

All questions of Boats and Streams for SSC CGL Exam

If 60% of the downstream speed of a boat is the same as the upstream speed of the boat. The speed of stream is what percentage of the speed of the boat in still water?
  • a)
    20
  • b)
    25
  • c)
    30
  • d)
    40
Correct answer is option 'B'. Can you explain this answer?

Iq Funda answered
60% of downstream speed = Upstream speed
Downstream speed : Upstream speed = 100 : 60 = 5 : 3
Stream speed : Speed of the boat in still water 

Hence, Option B is correct.

The time taken by a boat while covering a certain distance upstream is thrice the time taken by it while covering the same distance in still water. If the upstream speed is 6 km/hr, what is the downstream speed?
  • a)
    10 km/hr
  • b)
    15 km/hr
  • c)
    16 km/hr
  • d)
    30 km/hr
Correct answer is option 'D'. Can you explain this answer?

Ishaan Roy answered
Given Information:
- Upstream speed = 6 km/hr
- Time taken upstream = 3 times the time taken in still water

Let's assume:
- Speed of the boat in still water = x km/hr
- Time taken in still water = t hours

Calculating Time taken upstream and downstream:
- Time taken upstream = Distance/ (x-6) (since speed upstream = x - 6)
- Time taken downstream = Distance/ (x+6) (since speed downstream = x + 6)

Given that time taken upstream = 3 times time taken in still water:
Distance/ (x-6) = 3t

Distance/ (x-6) = 3t
Distance/ (x-6) = t
3t = t
3 = 1
This is not possible as the times cannot be equal. Hence, the assumption that time taken in still water is t hours is incorrect.

Re-assuming:
Let's assume the time taken in still water = 1 hour.

Given that time taken upstream is 3 times time taken in still water:
Time taken upstream = 3 hours

Now, substituting the values:
Distance/ (x-6) = 3
Distance = 3(x-6)

Given that time taken downstream is 1 hour (time taken in still water):
Distance/ (x+6) = 1
Distance = x+6

Equating the two expressions for Distance:
3(x-6) = x+6
3x - 18 = x + 6
2x = 24
x = 12
Therefore, the downstream speed is x + 6 = 12 + 6 = 18 km/hr
Hence, the correct answer is 30 km/hr (Option D).

If the speed of a stream is 5 km/hr and the speed of a boat in still water is 15 km/hr, what is the downstream speed of the boat?
  • a)
    20 km/hr
  • b)
    25 km/hr
  • c)
    30 km/hr
  • d)
    40 km/hr
Correct answer is option 'A'. Can you explain this answer?

Arnav Saini answered
Understanding the Problem:
Given:
Speed of the stream = 5 km/hr
Speed of the boat in still water = 15 km/hr

Downstream Speed Formula:
The downstream speed of the boat is the sum of the speed of the boat in still water and the speed of the stream.

Calculating Downstream Speed:
Downstream speed = Speed of boat in still water + Speed of stream
Downstream speed = 15 km/hr + 5 km/hr
Downstream speed = 20 km/hr
Therefore, the downstream speed of the boat is 20 km/hr. Hence, option 'A' (20 km/hr) is the correct answer.

The still water speed of a boat is 30 km/hr. It goes 28 km upstream in 1 hour 45 minutes. What is the downstream speed of the boat?
  • a)
    20 km/hr
  • b)
    27 km/hr
  • c)
    32 km/hr
  • d)
    44 km/hr
Correct answer is option 'D'. Can you explain this answer?

Malavika Rane answered
Understanding the Problem
To find the downstream speed of the boat, we first need to determine the effective speed of the boat while going upstream, and then use that to find the downstream speed.
Given Information
- Still water speed of the boat = 30 km/hr
- Distance traveled upstream = 28 km
- Time taken to travel upstream = 1 hour 45 minutes
Convert Time to Hours
- 1 hour 45 minutes = 1 + 45/60 = 1.75 hours
Calculate Upstream Speed
- Speed = Distance/Time
- Upstream Speed = 28 km / 1.75 hours = 16 km/hr
Calculate Effective Upstream Speed
The effective upstream speed (speed against the current) is the still water speed minus the speed of the current (x):
- Effective Upstream Speed = Still Water Speed - Current Speed
- 16 km/hr = 30 km/hr - x
Find Current Speed
- Rearranging gives us: x = 30 km/hr - 16 km/hr = 14 km/hr
Calculate Downstream Speed
The downstream speed (speed with the current) is the still water speed plus the speed of the current:
- Downstream Speed = Still Water Speed + Current Speed
- Downstream Speed = 30 km/hr + 14 km/hr = 44 km/hr
Conclusion
The downstream speed of the boat is 44 km/hr. Thus, the correct answer is option 'D'.

Chapter doubts & questions for Boats and Streams - Quantitative Aptitude for SSC CGL 2026 is part of SSC CGL exam preparation. The chapters have been prepared according to the SSC CGL exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for SSC CGL 2026 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

Chapter doubts & questions of Boats and Streams - Quantitative Aptitude for SSC CGL in English & Hindi are available as part of SSC CGL exam. Download more important topics, notes, lectures and mock test series for SSC CGL Exam by signing up for free.

Top Courses SSC CGL