Boats and Streams Aptitude Questions and Answers

Boats and Streams Aptitude Questions and Answers:-

Here i am going to provide you problems on boats and streams for SSC Exam,boat and stream Question and Answer for Bank Po, Percentage Question and Answer Lic exam. simply candidate can register and take online Quiz. Jobriya.co.in going to share with you boat and stream formula, boats and streams tricks,boats and streams shortcuts,percentage question and answers.in this chapter you know how you can solve percentage problems within second . here i am going to share percentage tricks,boats and streams shortcuts with example after that we provide boats and streams online quiz.

Boat and Stream Formula:- 

  • Speed of the boat against stream or while moving upstream = Speed of the boat in still water – Speed of the stream.
  • Speed of the boat with stream or while moving downstream= Speed of the boat in still water + Speed of the Stream.
  • If ‘p’ is the speed of the boat down the stream and ‘q’ is the speed of the boat up the stream, then,
  • Speed of the boat in still water = (p+q) / 2.
  • Speed of the boat of the water stream = (p-q) / 2.
  • These problems are governed by the following results: Downstream (along the current) speed (D) = Boat speed (B) + current (stream) speed (C).  D=B+C

Upstream (against the current) speed (U) = Boat speed – current (stream) speed. U=B–C

Speed of the boat = average of downstream and upstream speeds B = (D + U)/2

Speed of the current = half the difference of downstream and upstream speeds    C = (D – U)/2

Boat and Stream Short Cuts 

Boat and Stream Short Tricks 1:-  Given a boat travels downstream with speed d km/hr and it travels with speed ukm/hr upstream. Find the speed of stream and speed of boat in still water.

Let speed of boat in still water be bkm/hr and speed of stream be skm/hr.
Then b + s  = d and b – s = u.
Solving the 2 equations we get,
b = (d + u)/2
s = (d – u)/2

 

Boat and Stream Short Tricks 2: A man can row a boat, certain distance downstream in td hours and returns the same distance upstream in tu hours. If the speed of stream is s km/h, then the speed of boat in still water is given by

We know distance = speed * time
Let the speed of boat be b km/hr
Case downstream:
    d = (b + s) * td
Case upstream:
  d = (b – s) * tu
=>    (b + s) / (b – s) = tu / td
b = [(tu + td) / (tu – td)] * s

 

Boat and Stream Short Tricks  3: A man can row in still water at b km/h. In a stream flowing at  s km/h, if it takes him t hours to row to a place and come back, then the distance between two places, d is given by

Downstream:  Let the time taken to go downstream be td
d = (b + s) * td

Upstream: Let the time taken to go upstream be tu
d = (b – s) * tu

td + tu = t
[d / (b + s)] + [d / (b – s)] = t
So, d = t * [(b2 – s2) / 2b]
OR
d = [t * (Speed to go downstream) * (Speed to go upstream)]/[2 * Speed of boat or man in still water]

 

Boat and Stream Short Tricks  4:-  A man can row in still water at b km/h. In a stream flowing at s km/h, if it takes t hours more in upstream than to go downstream for the same distance, then the distance d is given by

Time taken to go upstream = t + Time taken to go downstream
(d / (b – s)) = t + (d / (b + s))
=> d [ 2s / (b2 – s2 ] = t
So, d = t * [(b2 – s2) / 2s]
OR
d = [t * (Speed to go downstream) * (Speed to go upstream)] / [2 * Speed of still water]

Example:-

Question:- A man cnn row a boat at 20 kmph in still water.If the speed of the stream is 6 kmph, what is the time taken to row a distance of 60 km downstream ?
Sol: Speed of downstream = boat speed + stream speed = 20 + 6 = 26 kmph
Time required to cover 60 km downstream = d/s = 60/26 = (30/13) hours.
Question:- The time taken by a man to row his boat upstream is twice the time taken by him to row the same distance downstream. If the speed of the boat in still water is 42 kmph, find the speed of the stream ?
Sol: The time taken to row his boat upstream is twice the time taken by him to row the same distance downstream. Therefore, the ratio of the time taken is (2:1). So, the ratio of the speed of the boat in still water to the speed of the stream = (2+1)/(2-1) = 3:1 .Thus, Speed of the stream = (42)/3 = 14 kmph.

Boat Stream Solved Problem

EX.1.A man can row upstream at 7 kmph and downstream at 10kmph.find man’s rate in still water and the rate of current.
Sol. Rate in still water=1/2(10+7)km/hr=8.5 km/hr.
Rate of current=1/2(10-7)km/hr=1.5 km/hr.
EX.2. A man takes 3 hours 45 minutes to row a boat 15 km downstream of a river and 2hours30minutes to cover a distance of 5km upstream. find the speed of the river current in km/hr.
Sol. rate downstream=(15/3 ¾)km/hr=(15*4/15)km/hr=4km/hr.
Rate upstream=(5/2 ½)km/hr=(5*2/5)km/hr=2km/hr.
Speed of current=1/2(4-2)km/hr=1km/hr
EX.3. a man can row 18 kmph in still water.it takes him thrice as long to row up as to row down the river.find the rate of stream.
Sol. Let man’s rate upstream be x kmph.then ,his rate downstream=3xkmph.
So,2x=18 or x=9.
Rate upstream=9 km/hr,rate downstream=27 km/hr.
Hence,rate of stream=1/2(27-9)km/hr=9 km/hr.
EX.4. there is a road beside a river.two friends started from a place A,moved to a temple situated at another place B and then returned to A again.one of them moves on a cycle at a speed of 12 km/hr,while the other sails on a boat at a speed of 10 km/hr.if the river flows at the speed of 4 km/hr,which of the two friends will return to placeA first?
Sol. Clearly the cyclist moves both ways at a speed of 12 km/hr.
The boat sailor moves downstream @ (10+4)i.e.,14 km/hr and upstream @ (10-4)i.e.,
6km/hr.
So,average speed of the boat sailor=(2*14*6/14+6)km/hr
=42/5 km/hr=8.4 km/hr.
since the average speed of the cyclist is greater ,he will return ta A first.
EX.5. A man can row 7 ½ kmph in still water.if in a river running at 1.5 km/hr an hour,it takes him 50 minutes to row to a place and back,how far off is the place?
Sol. Speed downstream =(7.5+1.5)km/hr=9 km/hr;
Speed upstream=(7.5-1.5)kmph=6kmph.
Let the required distance be x km.then,
x/9+x/6=50/60.
2x+3x=(5/6*18)
5x=15
x=3.
Hence,the required distance is 3km.
EX.6. In a stream running at 2kmph,a motar boat goes 6km upstream and back again to the starting point in 33 minutes.find the speed of the motarboat in still water.
Sol.let the speed of the motarboat in still water be x kmph.then,
6/x+2 +6/x-2=33/60
11×2-240x-44=0
11×2-242x+2x-44=0
(x-22)(11x+2)=0
x=22.
EX.7.A man can row 40km upstream and 55km downstream in 13 hours also, he can row 30km upstream and 44km downstream in 10 hours.find the speed of the man in still water and the speed of the current.
Sol.let rate upstream=x km/hr and rate downstream=y km/hr.
Then,40/x +55/y =13…(i) and 30/x +44/y =10
Multiplying (ii) by 4 and (i) by 3 and subtracting ,we get:11/y=1 or y=11.
Substituting y=11 in (i),we get:x=5.
Rate in still water =1/2(11+5)kmph=8kmph.
Rate of current=1/2(11-5)kmph=3kmph

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Boats and Streams Questions Answers

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