A man can row three-quarters of a km against the stream in 45/4 minutes and return 15/2 minutes. The

Sushmita Ghanty   9 years AGO

three quarters of a km= 750 m
45/4 mins= 675 secs, 15/2 mins= 450 secs
rate of upstream = (750/675)m/sec= 10/9 m/sec
rate of downstream = (750/450)m/sec = 5/3 m/sec
The speed of the main in still water= 1/2 * (10/9 + 5/3) = 25/18 m/sec = (25/18 * 18/5)= 5 km/hr

Like? Yes (26) | No (3)  

Priya   9 years AGO

distance=3/4 km
speed upstream= (3/4)/(45/4)km/min=1/15
speed downstream=(3/4)/7.5km/min=1/10
speed in still water= 1/2*(1/15+1/10)=1/12km/min= 5 km/kr

Like? Yes (18) | No (3)  

Veerraj Chauhan   9 years AGO

Rate Downstream = (3/4)/(15/2)= 1/10 km/min
= (1/10)*60= 6 km/hr

Rate Upstream = (3/4)/(45/4)= 1/15 km/min
= (1/15)*60= 4 km/hr

Rate in still water = 1/2 (6+4) = 5km/hr

Like? Yes (10) | No (1)  

Narendra Gopi   9 years AGO

We can write three-quarters of a kilometre as 750 metres,

and 11 minutes as 675 seconds.

Rate upstream =750/675m/sec =10/9m/sec.

Rate downstream =750/450 m/sec=5/3m/sec.

Rate in still water = 1/2(10/9+5/3)m/sec = 25/18m/sec
= 25/18x18/5km/hr
= 5 km/hr.

Like? Yes (7) | No (1)  

ABHINAV PUSHPAM   9 years AGO

Distance = 3/4 km
Time taken to travel upstream = 11 1/4 minutes = 45/4 minutes
= 45/(4×60)hours = 3/16 hours
Speed upstream = Distance/Time=(3/4)/(3/16) = 4 km/hr
Time taken to travel downstream = 7 1/2 minutes = 15/2 minutes
= 15/(2×60) hours = 1/8 hours
Speed downstream = Distance/Time=(3/4)/(1/8)= 6 km/hr
Rate in still water = (6+4)/2=10/2=5 kmph

Like? Yes (2) | No   

aman aditya   9 years AGO

speed of man against the stream=4km/hr
speed of man with the stream= 6km/hr
speed in still water=5km/hr

Like? Yes (2) | No   

Archie   9 years AGO

Dist covered =3/4 km
Speed upstream ={(3/4)/(3/16)}km/hr=4km/hr
Speed downstream={(3/4)/(1/8)}km/hr=6kmph
Speed of man in still water ={4+6}/2 =5km/hr

Like? Yes (2) | No   

Pulkit   9 years AGO

Basically for against the stream take velocity as (velocity in still water - velocity against the stream) and for downstream add both velocities and apply v=km/hr

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Soma Naresh   9 years AGO

upstream speed(x)=0.750 km/(45/4) min
x=4 kmph
downstream speed (y) =0.750 km/(15/2) min
y=6 kmph
speed in still water=0.5 (x+y)
0.5 (4+6)
0.5×10
5kmph

Like? Yes (1) | No   

sudiptaa   9 years AGO

Rate upstream = 750/675 m/sec = 10/9 m/sec.

Rate downstream = 750/450 m/sec = 5/3 m/sec.
Rate in still water = 1/2( 10/9 +5/3) m/sec
= 25/18 m/sec
= 25/18 x 18/5 km/hr
= 5 km/hr.

Like? Yes (1) | No   

Abhisheak Kumar Missu   9 years AGO

speed of man in upstream=3/4*4/45=1/15km/m
speed of man in downstream=3/4*2/15=1/10km/m
speed of man in still water=1/15+1/10/2=5/60km/m=5km/hr

Like? Yes (4) | No (3)  

praveendas   9 years AGO

if he covers 3/4 distance in 45/4 min..in order to cover the full distance required time is5min.from this the speed is4km/hr
towards downstream the time taken to cover 3/4 km is 15/2..therfore to cover 1 km the required time is10 min..the speed is 6km/hr..
the avg of these two gives..speed of the man in still water which is (6+4)/2=5km/hr

Like? Yes (1) | No   

shivani gupta   9 years AGO

rat upstream=750/675m/sec=10/9 m/sec
rate downstream=750/450=5/3m/sec
rate instill water=1/2(a+b)
1/2(10/9+5/3)25/18m/sec=5km/hr

Like? Yes (1) | No   

Dinesh kumar   9 years AGO

3/4 km against the stream = 45/4 min
3/4 km parallel to stream = 15/2 min
3 km against the stream = 45 min
3 km parallel to stream = 30 min
Therefore ,against stream the speed is 4km/hr
for the stream the speed is 6km/hr

stream speed is (6-4)/2=1km/hr

Like? Yes (3) | No (2)  

PRITI MISHRA   9 years AGO

s=vt
velocity of man against the stream is (3/4) / ((45/4)/60) = 4 KM/H
velocity of man towards the stream is (3/4) / ((15/2)/60) =6
speed of the man in still water= (4+6)/2 = 5 km/hr

Like? Yes (2) | No (1)  

anand vijay   9 years AGO

let the speed of the man in still water be x and the speed of the stream be y
hence we have the two equation
going against the stream 3/4(x-y)=45/60*4
x-y = 4.......................(i)
going with the stream 3/4(x+y)=15/60*2
x+y = 6.......................(ii)
on solving (i) & (ii) we get
x=5, and y=1
hence , the speed of the man in still water= 5km/hr
option 9)

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pankaj kumar   9 years AGO

a man speed is 4 kmph against stream and return speed is 6 kmph, so the speed of man in still water is as average speed 5 kmph

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Piyush Telang   9 years AGO

Distance Traveled Upstream and Downstream (Dist) = 3/4 km
Time Taken while going upstream (Tu)= 45/4 min = 3/16 hours
Time Taken while going downstream (Td) = 15/2 min = 1/8 hours
Speed while going upstream (U) = (Dist)/(Tu) = (3/4) / (3/16) = 4 km/hr
Speed while going downstream (D) = (Dist)/(Td) = (3/4) / (1/8) = 6 km/hr
Speed of Still water is given as = ( U + D ) / 2 = (4+6)/2 = 5 km/hr

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SOMA NARESH   9 years AGO

upstream speed(x)=0.750 km/(45/4) min
x=4 kmph
downstream speed (y) =0.750 km/(15/2) min
y=6 kmph
speed in still water=0.5 (x+y)
0.5 (4+6)
0.5×10
5kmph

Like? Yes (1) | No   

Ashu Kumar   9 years AGO

LET SPEED OF STREAM IS U & MAN IN STILL WATER IS V
V-U=3*4*60/(4*45)=4
V+U=3*2*60/(4*15)=6
SO V=5

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Riyashree Mukherjee   9 years AGO

Rate at still water=1/2(rate of upstream+rate of downstream)=5km/hr

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Ravi shankar   9 years AGO

(b-w)*(1/4)=1 and (b+w)*(1/8)=3/4. solving this we get b=5kmph

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krishna chandrika   9 years AGO

speed of upstream = (3*4*60)/(4*45) = 4km/hr
speed of down stream = (3*2*60)/(4*15) = 6km/hr

speed of man in still water = 1/2(speed of upstream+speed of down stream)
=1/2(4+6)
=5km/hr

Like? Yes (1) | No   

Ajay Kumar Gupta   9 years AGO

We can write three-quarters of a kilometre as 750 metres,

and 45/4 minutes as 675 seconds.

Rate upstream = (750/675) m/sec = 10/9 m/sec.
Rate downstream =(750/450) m/sec = 5/3 m/sec.
Rate in still water =1/2(10/9+5/3)m/sec = 25/18 m/sec
=(25/18)*(18/5)=5 km/hr

Like? Yes (1) | No   

Kowshik Biswas   9 years AGO

man + water speed =6 km/h
(in 30/4 min it can row 3/4 km so speed of man + water =3*4*60/4*30=6 km/h )
man - water speed =4 km/h
(in 45/4 min it can row 3/4 km so speed of man - water =3*2*60/4*15=4 km/h )
so, man + water = 6 km/h (speed)
man - water = 4 km/h (speed)
so,man speed in steel water is 5 km per hour

Like? Yes (1) | No   

Deepak kushwaha   9 years AGO

Speed of man in upstream is 4kmph
Speed of man in downstream is 6kmph
Let the speed of man in still water be x & speed od of water be y
then,
x+y=6..........(1)
x-y=4...........(2)
from eqn(1)&(2)
x=5(option 9)

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prem kishor   9 years AGO

against the stream
750/v-s=45/4

750/v+s=15/2

after solving eqn we will get v=5km/hr

Like? Yes (2) | No (1)  

vimal tiwari   9 years AGO

speed of man = (going speed - return speed )/2;
going speed = (3/4) / (45/(4*60));
return speed = (3/4) / (15/(2*60));

speed of man = 5 km/hr

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siddharth prakash singh   9 years AGO

Assuume speed in still water =x and speed of stream=y. Down stream speed will be x+y and upstream speed will be x-y.
Solving given conditions. We get two equations giving x=5 and y=1.

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Arju   9 years AGO

Answer: Option 9

Explanation:

We can write three-quarters of a kilometre as 750 metres,

and 45/4 minutes as 675 seconds and return 15/2minutes as 450seconds.

Rate upstream = 750/675 m/sec = 10/9 m/sec.

Rate downstream = 750/450 m/sec = 5/3 m/sec.

Rate in still water = 1/2( 10/9 + 5/3) m/sec

= 25/18 m/sec

= 25/18 x 18/5 km/hr
= 5 km/hr.

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anubhav kumar gupta   9 years AGO

total distance =3 /4km
let still water speed be x
and during upstream & downstream be = y
therefore,
speed during upstream i.e (x-y)=3/4 km*((4*60)/(45*1))
=4 -----(i)
speed during downstream i.e (x+y)=3/4*((2*60)/(15*1))
=6 -------(ii)
adding equation (i) and (ii)
we get
x+y+x-y=4+6
2x=10
x=5km/hr

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UJJWAL KANT   9 years AGO

Given distance =3/4km
for upstream
time=45/(4*60)=3/16 hr
speed=4kmph
for downstream
time=1/8hr
speed=6kmph
now
spd upstrm=spd of boat-spd of strm
4=SB-SS.............(1)

spd dwmstrm=spd of boat+spd of strm
6=SB+SS.............(2)
on solving both eqn 1 and 2 we get
spd of boat =5kmph

Like? Yes (1) | No   

sourav pal   9 years AGO

We can write three-quarters of a kilometre as 750 metres,

and 11 minutes as 675 seconds.

Rate upstream = 750 m/sec = 10 m/sec.
675 9

Rate downstream = 750 m/sec = 5 m/sec.
450 3

Rate in still water = 1 10 + 5 m/sec
2 9 3

= 25 m/sec
18

= 25 x 18 km/hr
18 5

= 5 km/hr.

Like? Yes (1) | No (1)  

Anuj Rai   9 years AGO

3/4th of a kilometer is 750

Time 45/4*60=675

upstream = 750/675=10/9
downstream = 750/450=5/3
rate in still water 1/2(10/9+5/3)
25/18
he speed(in km/hr) of the man in still water is
25/18*18/5=5kmph

Like? Yes (2) | No (2)  

SURAJ NIRALA   9 years AGO

let the speed of man in still water is x and the speed of the speed of stream is y km/h
now spead of man in the direction of stream will be (x+y) km/h
speed of man in the opposite direction of stream will be (x-y) km/h
Now as per question
(3/4)/(x-y) = (45/4)/60
i.e.
x-y =4 …………(1)
(3/4)/(x+y) =(15/2)/60
i.e.
x+y = 6 ………..(2)
On solving equation 1 and 2 we get
X=5 & y= 1
i.e. speed of man = x= 5km/h

Like? Yes (3) | No (3)  

Dinni   9 years AGO

We can write three-quarters of a kilometre as 750 metres,

and 11 minutes as 675 seconds.

Rate upstream = 750 m/sec = 10 m/sec.
675 9
Rate downstream = 750 m/sec = 5 m/sec.
450 3
Rate in still water = 1 10 + 5 m/sec
2 9 3
= 25 m/sec
18
= 25 x 18 km/hr
18 5
= 5 km/hr.

Like? Yes (1) | No (1)  

RAKESH ARYA   9 years AGO

(x-y)*(45/4) = (x+y)*(15/2)
=> x = 5y
=> y = 1/5

then , (x-x/5) * 45/( 4 * 60) = 3/4
=> x =5 km/hr

Like? Yes (1) | No (1)