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A Learning Portal from Recruitment India
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?
2hr. 40min
1 hr. 20min
2hr. 48min
1hr. 24min
Answer with explanation
Answer: Option DExplanation
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
Workspace
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?
2 km/hr
2.25 km/hr
1.5 km/hr
4 km/hr
Answer with explanation
Answer: Option AExplanation
Workspace
Guddi’s swimming speed in still water to the speed of river is 7:1. She swims 4.2 km up the river in just 14 min. How much time will Guddi take to swim 18.4 km down the river?
12 minutes
11 minutes
46 minutes
23 minutes
Answer with explanation
Answer: Option CExplanation
Workspace
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?
2 km/hr
2.5 km/hr
1 km/hr
1.5 km/hr
Answer with explanation
Answer: Option AExplanation
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
Workspace
A man can push upstream at 6km/hr and downstream at 10 km/hr. Discover man’s rate in still water and the rate of the momentum.
7,9 km/hr
6,8 km/hr
4,5 km/hr
5,6 km/hr
Answer with explanation
Answer: Option BExplanation
Speed upstream =6 km/hr` Speed downstream = 10 km/hr` Rate in still water = 1/2 (10-6) km/hr. = 6km/hr` Rate of the current = 1/2 (10+6) km/hr =8 km/hr
Workspace
If a man rows at 5 km/hr in still water and 3.5 km/hr against the current,then his rate along the current is
8.5 km/hr
4.25 km/hr
6 km/hr
Answer with explanation
Answer: Option AExplanation
If The speed of boat or boatman in calm water is u kmph and The speed of water or stream is v kmph, then:In water, the speed along with stream= (u + v) kmph
Speed of current = 5 – 3.5 = 1.5 km/hr.
So the speed of man along the current = 5 + 1.5 = 6.5 km/hr
Workspace
A man can row 9 1/3 km/hr in still water and he finds that is thrice as much time to row u p than as to row down the same distance in river. The speed of the current is
1 ¼ km/hr
3 1/3 km/hr
4 2/3 km/hr
3 1/9 km/hr
Answer with explanation
Answer: Option CExplanation
Explanation:
Let Speed upstream = x km/hr
Workspace
A motorboat in still water travels at a speed of 36 km/hr. It goes 56 km upstream in 1 hour 45 monutes. The time taken by it to cover the same distance down the stream will be
2 hour 21 minutes
2 hour 25 minutes
1 hour 24 minutes
3 hour
Answer with explanation
Answer: Option CExplanation
Workspace
A man rows downstream 32 km and 14 km upstream. If he takes 6 hours to cover each distance, then the velocity (in kmph) of the current is
1.75 kmph
3 kmph
1.5 kmph
2 kmph
Answer with explanation
Answer: Option CExplanation
Rate downstream = [32/6] kmph; Rate upstream = [14/6] kmph.
=> Velocity of current = 1/2[32/6 – 14/6] kmph
= 3/2 kmph
= 1.5 kmph
Workspace
For a motorboat that covers a certain distance downstream in 2 hours & returns in 3 hours, what would be its speed in still water if the speed of stream is 6 km/hr?
15 km/hr
9 km/hr
36 km/hr
30 km/hr
Answer with explanation
Answer: Option DExplanation
Workspace
A man can swim in still water at 4.5 km/h, but takes twice as long to swim upstream than downstream. The speed of the stream is?
2.25
7.5
1.5
3
Answer with explanation
Answer: Option CExplanation
Explanation:
M = 4.5
S = x
DS = 4.5 + x
US = 4.5 + x
4.5 + x = (4.5 – x)2
4.5 + x = 9 -2x
3x = 4.5
x = 1.5
Workspace
A person can swim in still water at 4 km/h. If the speed of water 2 km/h, how many hours will the man take to swim back against the current for 6km?
4 (1/2)
3
4
Insufficient data
Answer with explanation
Answer: Option BExplanation
Explanation:
M = 4
S = 2
US = 4 – 2 = 2
D = 6
T = 6/2 = 3
Workspace
A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?
40 minutes
1 hr 30 min
1 hour
1 hr 15 min
Answer with explanation
Answer: Option DExplanation
Workspace
A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream
2 hours
4 hours
3 hours
5 hours
Answer with explanation
Answer: Option BExplanation
Solution:
Speed downstream
= (13 + 4) km/hr
= 17 km/hr
Time taken to travel 68 km downstream
= 6817
6817
hours
= 4 hours
Workspace
A man can row 9 (1/3) kmph in still water and finds that it takes him thrice as much time to row up than as to row down the same distance in the river. What is speed of the current ?
3(1/2) km/hr
5km/hr
8 (3/2)km/hr
4 (2/3) km/hr
Answer with explanation
Answer: Option DExplanation
Let man’s rate upstream be x km/hr. Then his rate downstream is 3 x km/hr
Given:
Speed in still water = 9 (1/3) = 28/3 km/hr
i.e, ½ (a+b) = 28/3 km/hr
½ (x+3x) = 28/3
2x = 28/3 x = 28/ 2 x 3 = 14/3 km/hr
rate upstream b = 14/3 km/hr and
rate downstream a = 14/3 x 3 = 14 km/hr
speed of the current = ½ (a-b) = ½ (14 – 14/3)
= ½ (42-14/3) = 28/6 = 4 (2/3) km/hr
Workspace
The speed of the boat in still water is 5 times that of current, it takes 1.1 hour to row to point B from point A downstream. The distance between point A and point B is 13.2 km. How much distance (in km) will it cover in 312 minutes upstrem?
43.2
48
41.6
44.8
Answer with explanation
Answer: Option CExplanation
Workspace
A boat takes half time in moving a certain distance downstream than upstream. What is the ratio between the rate in still water and rate of current?
1 : 2
3 : 1
2 : 1
1 : 3
Answer with explanation
Answer: Option BExplanation
Let the speed of the boat in still water be 4 km/hr and speed of the current be u km/hr.
Rate downstream = (u + v) km/hr.
Rate upstream = (u- v)km/hr
Let the distance covered in each case be x km.
Then 2x/(u + v) = x / (u – v)
=> 2 (u – v) = ( u + v)
=> u =3v
=> u/v =3/1
Workspace
A man rows ‘k’ km upstream and back again downstream to the same point in H hours. The speed of rowing in still water is s km/hr and the rate of stream is r km/hr. Then?
(r + s) = kH / (r -s)
(s2-r2) =2sk /H
rs = kH
None of the above
Answer with explanation
Answer: Option BExplanation
Time taken to cover total distance = H hrs.
Speed of upstream = s – r. Speed of downstream = s + r.
∴ k / (s + r) + k / (s – r) = H ⇒(s2-r2) =2sk /H
Workspace
A boat covers a certain distance downstream in 2 hour, while it comes back in 2 1/2 hours. If the speed of the stream be 5 kmph, what is the speed of the boat in still water?
45 kmph
35 kmph
30 kmph
40 kmph
Answer with explanation
Answer: Option AExplanation
Let the speed of the boat in still water be x kmph. Then,
Speed downstream = (x + 5) kmph,
Speed upstream = (x – 5) kmph.
(x + 5)*2 = (x – 5)*5/2
X = 45 kmph
Workspace