Aptitude practices on Boats and Streams

Aptitude questions and answers on Boats and Streams

 

1) The speed of a boat in still water is 5km/hr. If the speed of the boat against the stream is 3 km/hr, what is the speed of the stream?

  1. 1.5 km/hr
  2. 2 km/hr
  3. 2.5 km/hr
  4. 1 km/hr

The correct answer is B

Answer with explanation:

Let the speed of stream = X km/hr

Speed of boat = 5 km/hr

Speed upstream = 3km/hr

Apply formula: Speed upstream = speed of boat - speed of stream

∴ 3 = 5 - X

X = 5 - 3 = 2 km/hr


2) A man rows downstream at 20 km/hr and rows upstream at 15 km/hr. At what speed he can row in still water?

  1. 17.5 km/hr
  2. 18 km/hr
  3. 20.5 km/hr
  4. 22 km/hr

The correct answer is A

Apply formula: Speed in still water = Apti Boat and streams 9(speed downstream + speed upstream)

Speed downstream = 20 km/hr

Speed upstream = 15 km/hr

∴ Required speed = Apti Boat and streams 10 (20 + 15) km/hr

Apti Boat and streams 11 ∗ 35 = 17.5 km/hr


3) A boat covers 800 meters in 600 seconds against the stream and returns downstream in 5 minutes. What is the speed of the boat in still water?

  1. 1 m/s
  2. 1.5 m/s
  3. 2 m/s
  4. 2.5 m/s

The correct answer is C

Answer with explanation:

Speed upstream = Apti Boat and streams 19 = Apti Boat and streams 20 = Apti Boat and streams 21 m/s

Speed downstream = Apti Boat and streams 22 = Apti Boat and streams 23 = Apti Boat and streams 24 m/s

Apply formula: Speed in still water = Apti Boat and streams 25 (speed downstream + speed upstream)

X = Apti Boat and streams 26 m/s

Y = Apti Boat and streams 27 m/s

∴ Speed in still water = Apti Boat and streams 28 Boats and streams Sign Apti Boat and streams 29 + Apti Boat and streams 30Boat and streams Sign 2

Apti Boat and streams 31 ∗ 4 = 2 m/s


4) A man can row a boat at a speed of 20 km/hr in still water. If the speed of the stream is 5 km/hr, in what time he can row a distance of 75 km downstream?

  1. 1.5 hours
  2. 2 hours
  3. 2.5 hours
  4. 3 hours

The correct answer is D

Answer with explanation:

Speed of boat = 20 km/hr

Speed of stream = 5 km/hr

∴ Speed downstream = 20 + 5= 25 km/hr

Required Time = Apti Boat and streams 32 = Apti Boat and streams 33 = 3 hours


5) A man swimming in a river that is flowing at 3Apti Boat and streams 34 km/hr finds that in a given time he can swim twice as far downstream as he can swim upstream. What will be his speed in still water?

  1. 9.5 km/hr
  2. 10 lm/hr
  3. 10.5 km/hr
  4. 11 km/hr

The correct answer is C

Answer with explanation:

Let the man swims at X km/hr in still water.

As per the question, he covers twice the distance downstream as he covers upstream in a given time.

Distance = Speed ∗ Time

∴ Speed downstream ∗ Time = 2 (Speed upstream ∗ Time)

Time is the same in both cases.

∴ X+3 Apti Boat and streams 35 =2∗ Boats and streams Sign X - 3 Apti Boat and streams 36 Boats and streams Sign 2

X + Apti Boat and streams 37 = 2∗ Boats and streams Sign X -Apti Boat and streams 38Boats and streams Sign 2

X + Apti Boat and streams 39 =2X - 7

X-2X = -7 - Apti Boat and streams 40

X = Apti Boat and streams 41 = 10.5 km/hr


6) A man swimming in a river that is flowing at 3Apti Boat and streams 34 km/hr finds that in a given time he can swim twice as far downstream as he can swim upstream. What will be his speed in still water?

  1. 9.5 km/hr
  2. 10 lm/hr
  3. 10.5 km/hr
  4. 11 km/hr

The correct answer is C

Answer with explanation:

Let the man swims at X km/hr in still water.

As per the question, he covers twice the distance downstream as he covers upstream in a given time.

Distance = Speed ∗ Time

∴ Speed downstream ∗ Time = 2 (Speed upstream ∗ Time)

Time is same in both the cases.

∴ X+3 Apti Boat and streams 35 =2∗ Boats and streams Sign X - 3 Apti Boat and streams 36 Boats and streams Sign 2

X + Apti Boat and streams 37 = 2∗ Boats and streams Sign X -Apti Boat and streams 38Boats and streams Sign 2

X + Apti Boat and streams 39 =2X - 7

X-2X = -7 - Apti Boat and streams 40

X = Apti Boat and streams 41 = 10.5 km/hr


7) A man can row at 12 km/hr in still water. He finds that he takes twice as much time to row upstream than to row downstream when he covers a certain distance. Find the speed of the stream.

  1. 4 km/hr
  2. 3 km/hr
  3. 4.5 km/hr
  4. 3.5 km/hr

The correct answer is A

Answer with the explanation:

As per the question, he takes twice the time when he rows upstream than rowing downstream.

Time is inversely proportioned to speed. So he rows at twice the speed when moving along the stream than moving against the stream.

Let his speed upstream = X km/hr

And, his speed downstream = 2X

∴ Speed in still water = 1/2 (2X+X) = 1.5 X km/hr

As per the question;

1.5X = 12 km/hr

X = Apti Boat and streams 42 =8 km/hr

Speed upstream = 8 km/hr

So, speed downstream = 2 ∗ 8= 16 km/hr

Speed of current = Apti Boat and streams 43 (speed downstream - speed upstream)

Apti Boat and streams 44 (16 - 8)

Apti Boat and streams 45 * 8 = 4 km/hr


8) A boat takes 6 hours to move downstream from point P to Q and to return to point P moving upstream. If the speed of the stream is 4 km/hr and the speed of the boat in still water is 6 km/hr, what is the distance between point P and Q?

  1. 8 km
  2. 9 km
  3. 10 km
  4. 11 km

The correct answer is C

Answer with the explanation:

Let the distance between points P and Q = X km

Speed downstream = 6 + 4= 10 km/hr

Speed upstream = 6 - 4 = 2 km/hr

Time = Apti Boat and streams 46

So, as per question;

Apti Boat and streams 47 + Apti Boat and streams 48 = 6 hours

Apti Boat and streams 49 = 6

6X = 60

X = 10 km


9) A man can swim in still water at 8 km/hr. If the river is flowing at 2km/hr he takes 80 minutes to reach a place and return back, how far is the place?

  1. 4 km
  2. 3 km
  3. 4.5 km
  4. 5 km

The correct answer is D

Answer with the explanation:

Let the place is X km far.

Speed downstream = 8+2=10 km/hr

Speed upstream = 8 - 2 = 6 km/hr

Time = Apti Boat and streams 50

So, as per question;

Apti Boat and streams 51 + Apti Boat and streams 52 = Apti Boat and streams 53

Apti Boat and streams 54 = Apti Boat and streams 55

30X + 18X = 240

48X = 240

X = Apti Boat and streams 56 = 5 km


10) A motorboat travels 16 km in 2 hours against the flow of the river and travels the next 8 km along with the flow of the river in 20 minutes. How long will it take a motorboat to travel 48 km in still water?

  1. 2.5 hours
  2. 3 hours
  3. 3.5 hours
  4. 4 hours

The correct answer is B

Answer with the explanation:

Speed = Apti Boat and streams 57

Speed upstream = Apti Boat and streams 58 = 8 km/hr

Speed downstream = Apti Boat and streams 59 = Apti Boat and streams 60 = 24 km/hr

∴ Speed in still water = Apti Boat and streams 61 (speed downstream +speed upstream)

Apti Boat and streams 62 (24+8)=16 km/hr

Required time = Apti Boat and streams 63

Apti Boat and streams 64 =3 hour


11) The velocity of a boat in still water is 9 km/hr, and the speed of the stream is 2.5 km/hr. How much time will the boat take to go 9.1 km against the stream?

  1. 1 hr. 20min
  2. 2hr. 40min
  3. 1hr. 24min
  4. 2hr. 48min

Answer: C

Answer with the Explanation:

ATQ,

Speed of boat in still water (Sb) = 9km/hr Speed of stream (Sc) = 2.5km/hr Distance against the stream = 9.1 km

Note: against the steam = upstream

Now, apply the formula:

The speed of boat upstream = speed of boat - the speed of the stream

The speed of upstream = 9-2.5 = 6.5km/hr Now, time= Distance/speed Time = 9.1/6.5, or 7/5 Or, time = 1[2/5] Or, 1hr + (2/5)*60 = 1hr + 24minutes


12) A man covers a distance of 36 km in 6 hours downstream and a distance of 40 km upstream in 8 hours. What is his speed in still water?

  1. 5.5km/hr
  2. 8km/hr
  3. 7km/hr
  4. None of these

Answer: A

Answer with the Explanation:

Upstream speed = distance covered in upstream/ time
Downstream speed = distance covered in downstream/ time

Upstream speed = 40/8 = 5kmph
Downstream speed = 36/6 = 6kmph
Now, speed of man in still water= (½) [speed in downstream + speed in upstream]

Or, the speed of man = [½][6+5] =5.5kmph


13) A boat travels upstream from Q to P and downstream from P to Q in 3 hours. If the distance between P to Q is 4km and the speed of the stream is 1kmph, then what is the velocity of the boat in still water?

  1. 3kmph
  2. 4kmph
  3. 5kmph
  4. 7.2kmph

Answer: A

Answer with the Explanation:

Let the velocity or speed of the boat in still water is x km/hr.
And the Speed of the stream = 1km/hr
So, the speed of the boat along the stream = (x+1) km/hr.
The speed of the boat against the stream = (x-1) km/hr.

Note: time = Distance / Speed

So, [4/ (x+1)] + [4/ (x-1)] = 3 hrs.

Note: go through the given options to get the answer quickly or solve the equation as follows:

Or, [4 (x+1+x-1)]/ [(x+1) (x-1)] = 3
Or, 8x = 3(x2-12)
Or, 8x = 3x2-3
Or, 3x2-8x-3=0
Or, 3x2- 9x+ x-3 = 0
Or, (x-3) (3x+1) = 0
Therefore x=3 or, x=-1/3 (speed can't be -ve)
Hence, the speed or velocity of the boat in still water is 3 km/hr.


14) The speed of the stream is 5km/hr. A boat goes 10 km upstream and returns back to the starting point in 50 minutes. Find the velocity of the boat in still water.

  1. 20km/hr
  2. 25km/hr
  3. 30km/hr
  4. 50km/hr

Answer: B

Answer with the Explanation:

Let the speed or velocity of the boat in still water is x km/hr
And the Speed of the stream = 5km/hr
So, the speed of the boat along the stream = (x+5) km/hr.
The velocity of the boat against the stream = (x-5) km/hr.

Note: Time = Distance / Speed

So, [10/ (x+5)] + [10/ (x-5)] = (50/60) hrs.


15) A boat travels from A to B along the stream and from B to A against the stream in 3 hours. If the velocity of the boat in still water is 4 km/hr, what is the distance between A and B?

  1. 8 km
  2. 10 km
  3. 12 km
  4. Data insufficient

Answer: D

Answer with the Explanation:

Let the distance between A and B is x km
The velocity of the boat in still water is 4km/hr.
Time taken to upstream and downstream is 3hr

Apply the formula:

Time = distance/speed
And Speed in the downstream = speed of the boat in still water+ speed of the stream
Speed in Upstream = speed of the boat in still water- speed of the stream

Let the speed of stream = y

So, (x/(4+y))+ (x/(4-y)) = 3hr.
We have one equation and two unknown expressions (x and y).
So, the given data is insufficient.

Tags:

  • Aptitude practices questions
  • Aptitude on boats and streams
  • Boats and Streams
  • interview aptitude questions

Leave a Comment

Your email address will not be published. Required fields are marked*

User Comments

notes4free

Tharun
at 2021-04-03 07:17:45

Wow this questions help me lot thank you notes4free , u r doing great and helping the students , keep on doing I am very happy with your works

Popular projects

Project Categories

notes4free donate

Please donate us for grow our platform ,donation starts from 1rs