Online Mock Test in Boat and Stream For Quantitative Aptitude for Competitive exams like IBPS BANK PO/Clerical,SBI,RRB,SSC,LIC,UPSC-CSAT,SCRA.MAT,CMAT,MBA,SNAP,CAT,NTSE,CLAT
Boat and Stream-Test 2
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Subject :- Quantitative Aptitude
Chapter :- Boat and Stream-Test 2
Questions :- 25
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Hari can row 12 kmph in still water when the river is running at 6 kmph it takes him 1
hour to row to a place and to come back. How far is the place?
Correct
Downstream Speed = 18 kmph
Upstream Speed = 6 kmph
Distance = x
x/18 + x/6 = 1
18x + 6x = 108
24x = 108
x = 4.5 km
OR USE FORMULA:
Distance = time [B2 – R2]/2*B
So distance = 1 * [122 – 62]/2*12
Distance = 108/24 = 4.5 km
Incorrect
Downstream Speed = 18 kmph
Upstream Speed = 6 kmph
Distance = x
x/18 + x/6 = 1
18x + 6x = 108
24x = 108
x = 4.5 km
OR USE FORMULA:
Distance = time [B2 – R2]/2*B
So distance = 1 * [122 – 62]/2*12
Distance = 108/24 = 4.5 km
Question 2 of 25
2. Question
1 points
The different between downstream speed and upstream speed is 2 kmph and the total
time taken during upstream and downstream is 2 hours. What is the upstream speed, if the downstream and upstream distance are 2 km each?
Correct
2/x + 2/(x+2) = 2.
x2 – 2 = 0
x = 1.414kmph
Incorrect
2/x + 2/(x+2) = 2.
x2 – 2 = 0
x = 1.414kmph
Question 3 of 25
3. Question
1 points
Rani can row 8 kmph in still water. If the river is running at 4 kmph it takes 90
minutes to row to a place and back. How far is the place?
Correct
Speed in still water = 8 kmph
Speed of the stream = 4 kmph
Upstream Speed = (8-4) = 4 kmph
Downstream Speed = (8+4) = 12 kmph
Total time = 90 minutes = 90/60 = 3/2 hrs
Let x is the distance
x/12 + x/4 = 3/2
x = 4.5 km
Incorrect
Speed in still water = 8 kmph
Speed of the stream = 4 kmph
Upstream Speed = (8-4) = 4 kmph
Downstream Speed = (8+4) = 12 kmph
Total time = 90 minutes = 90/60 = 3/2 hrs
Let x is the distance
x/12 + x/4 = 3/2
x = 4.5 km
Question 4 of 25
4. Question
1 points
Sumi can swim 6 kmph in still water. If the velocity of the stream be 2 kmph, the time
taken by her to swim to a place 24 km upstream and back, is?
Correct
Upstream speed = speed of man – speed of
stream=6 – 2 = 4
Downstream speed = speed of man + speed
of stream=6 + 2=8
Time taken to go upstream =
distance/speed = 24/4 =6 hour
Time taken to go downstream =
distance/speed =24/8 = 3 hour
Total time =6+3 = 9 hour
Incorrect
Upstream speed = speed of man – speed of
stream=6 – 2 = 4
Downstream speed = speed of man + speed
of stream=6 + 2=8
Time taken to go upstream =
distance/speed = 24/4 =6 hour
Time taken to go downstream =
distance/speed =24/8 = 3 hour
Total time =6+3 = 9 hour
Question 5 of 25
5. Question
1 points
Raghu can row 96 km downstream in 8 hours. If the speed of the current is 3 kmph,
then find in what time will be able to cover 12 km upstream?
Correct
Downstream speed = 96/8 = 12 kmph
Speed of current = 3 kmph
Speed of kamal in still water = 12-3 = 9 kmph
Upstream speed = 9-3 = 6 kmph
Time taken to cover 12 km upstream 12/6 =2 hours
Incorrect
Downstream speed = 96/8 = 12 kmph
Speed of current = 3 kmph
Speed of kamal in still water = 12-3 = 9 kmph
Upstream speed = 9-3 = 6 kmph
Time taken to cover 12 km upstream 12/6 =2 hours
Question 6 of 25
6. Question
1 points
A boat can cover 21 km in the direction of current and 15 km against the current in 3 hours each. Find the speed of current.
Correct
Downstream speed = 21/3 = 7 km/hr
Upstream speed = 15/3 = 5 km/hr
So speed of current = 1/2 * (7-5)
Incorrect
Downstream speed = 21/3 = 7 km/hr
Upstream speed = 15/3 = 5 km/hr
So speed of current = 1/2 * (7-5)
Question 7 of 25
7. Question
1 points
A boat in a river with speed of stream as 6 km/hr can travel 7 km upstream and back in 4
hours. What is the speed of the boat in still water?
Correct
Solution:
Let speed of boat is x km/hr
So
7/(x+6) + 7/(x-6) = 4
Solve, x = 8 km/hr [ignore the negative root
because speed cannot be negative]
Incorrect
Solution:
Let speed of boat is x km/hr
So
7/(x+6) + 7/(x-6) = 4
Solve, x = 8 km/hr [ignore the negative root
because speed cannot be negative]
Question 8 of 25
8. Question
1 points
A boat can cover 40 km upstream and 60 km downstream together in 13 hours. Also it can cover 50 km upstream and 72 km downstream together in 16 hours. What is the speed of the boat in still water?
Correct
Upstream speed in both cases is 40 and 50. Ratio
is 40 : 50 = 4 : 5. So let times in both cases be 4x
and 5x
Downstream speed in both cases is 60 and 72
resp. Ratio is 60 : 72 = 5 : 6. So let times in both
cases be 5y and 6y
So 4x + 5y = 13
and 5x + 6y = 16
Solve both, x = 2, y = 1
So upstream speed is = 40/4x = 5 km/hr
And downstream = 60/5y = 12 km/hr
So speed of boat is 1/2 * (5+12)
Incorrect
Upstream speed in both cases is 40 and 50. Ratio
is 40 : 50 = 4 : 5. So let times in both cases be 4x
and 5x
Downstream speed in both cases is 60 and 72
resp. Ratio is 60 : 72 = 5 : 6. So let times in both
cases be 5y and 6y
So 4x + 5y = 13
and 5x + 6y = 16
Solve both, x = 2, y = 1
So upstream speed is = 40/4x = 5 km/hr
And downstream = 60/5y = 12 km/hr
So speed of boat is 1/2 * (5+12)
Question 9 of 25
9. Question
1 points
A boat can row to a place 56 km away and come back in 22 hours. The time to row 21 km
with the stream is same as the time to row 12 km against the stream. Find the speed of boat in still water.
A boat travels downstream from point A to B and comes back to point C half distance between A and B in 18 hours. If speed of boat is still water is 7 km/hr and distance AB = 80 km, then find the downstream speed.
Correct
A to B is 80, so B to is 80/2 = 40 km
Let speed of current = x km/hr
So 80/(7+x) + 40/(7-x) = 18
Solve, x = 3 km/hr
So downstream speed = 7 + 3 = 10 km/hr
Incorrect
A to B is 80, so B to is 80/2 = 40 km
Let speed of current = x km/hr
So 80/(7+x) + 40/(7-x) = 18
Solve, x = 3 km/hr
So downstream speed = 7 + 3 = 10 km/hr
Question 11 of 25
11. Question
1 points
A boat can cover 20 km upstream and 32 km downstream together in 3 hours. Also it can
cover 40 km upstream and 48 km downstream together in 5 and half hours. What is the speed of the current?
Correct
Upstream speed in both cases is 20 and 20 resp.
Ratio is 20 : 40 = 1 : 2. So let times in both cases
be x and 2x
Downstream speed in both cases is 32 and 48
resp. Ratio is 32 : 48 = 2 : 3. So let times in both
cases be 2y and 3y
So x + 2y = 3
and 2x + 3y = 5 1/2
Solve both, x = 2, y = 0.5
So upstream speed is = 20/x = 10 km/hr
And downstream = 32/2y = 32 km/hr
So speed of boat is 1/2 * (32-10)=11 km/hr
Incorrect
Upstream speed in both cases is 20 and 20 resp.
Ratio is 20 : 40 = 1 : 2. So let times in both cases
be x and 2x
Downstream speed in both cases is 32 and 48
resp. Ratio is 32 : 48 = 2 : 3. So let times in both
cases be 2y and 3y
So x + 2y = 3
and 2x + 3y = 5 1/2
Solve both, x = 2, y = 0.5
So upstream speed is = 20/x = 10 km/hr
And downstream = 32/2y = 32 km/hr
So speed of boat is 1/2 * (32-10)=11 km/hr
Question 12 of 25
12. Question
1 points
Speed of boat in still water is 14 km/hr while the speed of current is 10 km/hr. If it takes a total of 7 hours to row to a place and come back, then how far is the place?
Correct
USE FORMULA:
Distance = total time * [B2 – R2]/2*B
So distance = 7 * [142 – 102]/2*14
Distance = 24 km
Incorrect
USE FORMULA:
Distance = total time * [B2 – R2]/2*B
So distance = 7 * [142 – 102]/2*14
Distance = 24 km
Question 13 of 25
13. Question
1 points
A man can row a certain distance downstream in 4 hours and return the same distance in 8 hours. If the speed of current is 16 km/hr, find the speed of man in still water.
Correct
Use formula:
B = [tu + td] / [tu – td] * R
B = [8+4] / [8-4] * 16
B = 48 km/hr
Incorrect
Use formula:
B = [tu + td] / [tu – td] * R
B = [8+4] / [8-4] * 16
B = 48 km/hr
Question 14 of 25
14. Question
1 points
There are 3 point A, B and C in a straight line such that point B is equidistant from points A and C. A boat can travel from point A to C downstream in 12 hours and from B to A
upstream in 8 hours. Find the ratio of boat in still water to speed of stream.
Correct
Let speed in still water = x km/hr, of current = y
km/hr
Downstream speed = (x+y) km/hr
Upstream speed = (x – y) km/hr
Let AC = 2p km. So AB = BC = p km.
So
2p/(x+y) = 12
And
p/(x-y) = 8
Divide both equations, and solve
x/y = 7/1
Incorrect
Let speed in still water = x km/hr, of current = y
km/hr
Downstream speed = (x+y) km/hr
Upstream speed = (x – y) km/hr
Let AC = 2p km. So AB = BC = p km.
So
2p/(x+y) = 12
And
p/(x-y) = 8
Divide both equations, and solve
x/y = 7/1
Question 15 of 25
15. Question
1 points
A boat can row 18 km downstream and back in 8 hours. If the speed of boat is increased to twice its previous speed, it can row same distance downstream and back in 3.2 hours. Find the speed of boat in still water.
Correct
Let speed of boat = x km/hr and that of stream =
y km/hr
So
18/(x+y) + 18/(x-y) = 8
when speed of boat becomes 2x km/hr:
18/(2x+y) + 18/(2x-y) = 3.2
Solve, x= 6 km/hr
Incorrect
Let speed of boat = x km/hr and that of stream =
y km/hr
So
18/(x+y) + 18/(x-y) = 8
when speed of boat becomes 2x km/hr:
18/(2x+y) + 18/(2x-y) = 3.2
Solve, x= 6 km/hr
Question 16 of 25
16. Question
1 points
A boat can cover 25 km upstream and 42 km downstream together in 7 hours. Also it can cover 30 km upstream and 63 km downstream together in 9 hours. What is the speed of the boat in still water?
Correct
Upstream speed in both cases is 25 and 30
resp. Ratio is 25 : 30 = 5 : 6. So let times in
both cases be 5x and 6x
Downstream speed in both cases is 42 and
63 resp. Ratio is 42 : 63 = 2 : 3. So let
times in both cases be 2y and 3y
So 5x + 2y = 7
and 6x + 3y = 9
Solve both, x = 1, y = 1
So upstream speed is = 25/5x = 5 km/hr
And downstream = 42/2y = 21 km/hr
So speed of boat is 1/2 * (5+21)
Incorrect
Upstream speed in both cases is 25 and 30
resp. Ratio is 25 : 30 = 5 : 6. So let times in
both cases be 5x and 6x
Downstream speed in both cases is 42 and
63 resp. Ratio is 42 : 63 = 2 : 3. So let
times in both cases be 2y and 3y
So 5x + 2y = 7
and 6x + 3y = 9
Solve both, x = 1, y = 1
So upstream speed is = 25/5x = 5 km/hr
And downstream = 42/2y = 21 km/hr
So speed of boat is 1/2 * (5+21)
Question 17 of 25
17. Question
1 points
A man rows to a certain place and comes back, but by mistake he covers 1/3rd more
distance while coming back. The total time for this journey is 10 hours. The ratio of
speed of boat to that of stream is 2 : 1. If the difference between upstream and
downstream speed is 12km/hr, then how much time will the man take to reach to
starting point from his present position?
Correct
Speed of boat and stream – 2x and x respectively. So downstream speed = 2x+x
= 3x, and upstream speed = 2x-x = x
Let total distance between points is d km
So he covered d km downstream, and while
coming back i.e. upstream he covers d +
1/3 *d = 4d/3 km
Total time for this journey is 10 hrs. So
d/3x + (4d/3)/x = 10
Solve, d = 6x
Now also given, that (2x+x) – (2x-x) = 12
Solve, x = 6
So d = 36 km
So to come to original point, he will have
to cover 1/3 * 36 = 12 km
And with speed 3x = 18
km/hr(downstream)
So time is 12/18 * 60 = 40 minutes
Incorrect
Speed of boat and stream – 2x and x respectively. So downstream speed = 2x+x
= 3x, and upstream speed = 2x-x = x
Let total distance between points is d km
So he covered d km downstream, and while
coming back i.e. upstream he covers d +
1/3 *d = 4d/3 km
Total time for this journey is 10 hrs. So
d/3x + (4d/3)/x = 10
Solve, d = 6x
Now also given, that (2x+x) – (2x-x) = 12
Solve, x = 6
So d = 36 km
So to come to original point, he will have
to cover 1/3 * 36 = 12 km
And with speed 3x = 18
km/hr(downstream)
So time is 12/18 * 60 = 40 minutes
Question 18 of 25
18. Question
1 points
A man can row at a speed of 15 km/hr in still water to a certain upstream point and
back to the starting point in a river which flows at 9 km/hr. Find his average speed
for total journey.
Correct
When the distance is same, then average
speed throughout journey would be:
Speed downstream * Speed upstream/speed
in still water.
So here average speed = (15+9)*(15-9)/15
= 9.6 km/hr
Incorrect
When the distance is same, then average
speed throughout journey would be:
Speed downstream * Speed upstream/speed
in still water.
So here average speed = (15+9)*(15-9)/15
= 9.6 km/hr
Question 19 of 25
19. Question
1 points
A boat takes 5 hours for travelling downstream from point A to point B and coming back to point C at 3/4th of total distance between A and B from point B. If the velocity of the stream is 3 kmph and the speed of the boat in still water is 9 kmph, what is the distance between A and B?
Correct
Let total distance from A to B= d km, So
CB = 3d/4 km
So
d/(9+3) + (3d/4)/(9-3) = 5
Solve, d = 24 km
Incorrect
Let total distance from A to B= d km, So
CB = 3d/4 km
So
d/(9+3) + (3d/4)/(9-3) = 5
Solve, d = 24 km
Question 20 of 25
20. Question
1 points
At its usual rowing rate, a boat can travel 18 km downstream in 4 hours less than it
takes to travel the same distance upstream. But if he the usual rowing rate for his 28-
km round trip was 2/3rd, the downstream 14 km would then take 12 hours less than
the upstream 14 km. What is the speed of the current?
Correct
Let speed of boat = x km/hr, and of current
= y km/hr
So
18/(x-y) = 18/(x+y) + 4
Gives x2 = 9y + y2……..(1)
Now when speed of boat is 2x/3
14/(2x/3 -y) = 14/(2x/3 +y) + 12
42/(2x-3y) = 42/(2x+3y) + 12
Gives 4×2 = 21y + 9y2…………(2)
From (1), put value of x2 in (2) and solve
Solving, x = 6, y = 3
Incorrect
Let speed of boat = x km/hr, and of current
= y km/hr
So
18/(x-y) = 18/(x+y) + 4
Gives x2 = 9y + y2……..(1)
Now when speed of boat is 2x/3
14/(2x/3 -y) = 14/(2x/3 +y) + 12
42/(2x-3y) = 42/(2x+3y) + 12
Gives 4×2 = 21y + 9y2…………(2)
From (1), put value of x2 in (2) and solve
Solving, x = 6, y = 3
Question 21 of 25
21. Question
1 points
A boat can row to a place 120 km away and come back in 25 hours. The time to row 24
km with the stream is same as the time to row 16 km against the stream. Find the
speed of current.
A man can row a certain distance downstream in 3 hours and return the same distance in 9 hours. If the speed of current is 18 km/hr, find the speed of man in still water.
Correct
Use formula:
B = [tu + td] / [tu – td] * R
B = [9+3] / [9-3] * 18
B = 36 km/hr
Incorrect
Use formula:
B = [tu + td] / [tu – td] * R
B = [9+3] / [9-3] * 18
B = 36 km/hr
Question 24 of 25
24. Question
1 points
Four times the downstream speed is 8 more than 15 times the upstream speed. If difference between downstream and upstream speed is 24 km/hr, then what is the ratio of speed in still water to the speed of the current?
Correct
Let speed in still water = x km/hr, of
current = y km/hr
So
4 (x+y) = 15(x-y) + 8
Solve, 11x – 19y + 8 = 0…….(1)
Also (x+y) – (x-y) = 24
So y = 12
Put in (1). x = 20
So x/y = 20/12 = 5/3
Incorrect
Let speed in still water = x km/hr, of
current = y km/hr
So
4 (x+y) = 15(x-y) + 8
Solve, 11x – 19y + 8 = 0…….(1)
Also (x+y) – (x-y) = 24
So y = 12
Put in (1). x = 20
So x/y = 20/12 = 5/3
Question 25 of 25
25. Question
1 points
A boat can cover 14 km upstream and 21 km downstream together in 3 hours. Also it
can cover 21 km upstream and 42 km downstream together in 5 hours. What is the speed of current?
Correct
Upstream speed in both cases is 14 and 21
resp. Ratio is 14 : 21 = 2 : 3. So let times in
both cases be 2x and 3x
Downstream speed in both cases is 21 and
42 resp. Ratio is 21 : 42 = 1 : 2. So let
times in both cases be y and 2y
So 2x + y = 3
and 3x + 2y = 5
Solve both, x = 1, y = 1
So upstream speed is = 14/2x = 7 km/hr
And downstream = 21/y = 21 km/hr
So speed of current is 1/2 * (21-7)=7 km/hr
Incorrect
Upstream speed in both cases is 14 and 21
resp. Ratio is 14 : 21 = 2 : 3. So let times in
both cases be 2x and 3x
Downstream speed in both cases is 21 and
42 resp. Ratio is 21 : 42 = 1 : 2. So let
times in both cases be y and 2y
So 2x + y = 3
and 3x + 2y = 5
Solve both, x = 1, y = 1
So upstream speed is = 14/2x = 7 km/hr
And downstream = 21/y = 21 km/hr
So speed of current is 1/2 * (21-7)=7 km/hr
