Latest Capgemini Aptitude Question SOLUTION: A motorboat whose speed is 15 kmph in still water goes 30 kmph downstream and comes back in a total of 4hrs 30min the speed of the stream in kmph is

• Placement Papers
• /
• Capgemini
• /
• Numerical Ability
• /
• Boats and Streams

Capgemini Question Papers: Capgemini Interview Experience(7) CAPGEMINI Company Profile

(#M40007947) CAPGEMINI Numerical Ability question aptitude Keep an EYE

A motorboat whose speed is 15 kmph in still water goes 30 kmph downstream and comes back in a total of 4hrs 30min the speed of the stream in kmph is

Asked In Capgemini (12 years ago)

Unsolved Read Solution (16)

Is this Puzzle helpful?   (65)   (24) Submit Your Solution Boats and Streams

Read Solution (16) :

pkamlesh  (12 years ago)

if we read question carefully...the speed of motor boat in downstream = 30 kmph(not 30 km)
therefore, speed of the stream= 30-15
=> 15 kmph

Is this solution Helpfull? Yes (41) | No (25)  

Vignesh  (12 years ago)

5 km/hr.

Let the speed of the stream be x km/hr. Then,

Speed downstream = (15 + x) km/hr,
Speed upstream = (15 - x) km/hr.
Therefore,
30/(15+x) + 30/(15-x) = 4(1/2)
=> 900/(225-x^2) = 9/2
=> 9x^2 = 225
=> x^2 = 25
=> x = 5

Is this solution Helpfull? Yes (32) | No (27)  

Sanjeevarayudu T  (12 years ago)

Speed in Down Stream(Boat+Stream)=30 Kmph
Speed in Still Water=15 Kmph
Speed of The Stream[(Boat+Stream)-Boat]=30-15 = 15 Kmph

Is this solution Helpfull? Yes (19) | No (11)  

saurabh mishra  (11 years ago)

Let the speed of the stream be x km/hr. Then,
speed downstream =(15 + x)km/hr

Speed upstream = (15 - x) km/hr.

Time= Distance/speed

30/15+x + 30/15-x = 9/2

On solving, 900/225-x^2 = 9/2

x^2=25

x=5km/hr



x = 5 km/hr.

Is this solution Helpfull? Yes (15) | No (10)  

aruna  (12 years ago)

5 kM/HR
Let the speed of the sream is x km/hr
speed of upstream=15+x
speed of down stream=15-x
30/15+x+30/15-x=9/2
solving this we get x^2=25
x=5 km/hr

Is this solution Helpfull? Yes (11) | No (22)  

Browns MN  (12 years ago)

5km/hr....let speed of stream be x then 30/(15-x)+ 30/(15+x)=9/2

x^2=25 so x=5!!!whe 30/(15-x)is time fo upstream and 30/(15+x)is downstream ..and the sum eqls total time..

Is this solution Helpfull? Yes (6) | No (11)  

saurabh mishra  (11 years ago)

Let the speed of the stream be x km/hr. Then,

Speed downstream = (15 + x) km/hr,

Speed upstream = (15 - x) km/hr.

30 + 30 = 4 1
(15 + x) (15 - x) 2
900 = 9
225 - x2 2
9x2 = 225

x2 = 25

x = 5 km/hr.

Is this solution Helpfull? Yes (5) | No (14)  

reeju  (11 years ago)

then how did it come back?? :)

Is this solution Helpfull? Yes (4) | No   

Gaurav Singh  (7 years ago)

speed of boat B is = (d+u) / 2
speed of stream S is= (d-u) / 2 where d for downstream and u for upstream
given that speed of boat =15km/h
and downstream d= 30 km/h
put the value 15= (30+u)/2
so we get u = 0 km/h
put the value in the stream formula s= (30-0)/2
speed of stream is = 15km /h ---> [answer].

we can prove it given time is 4hrs and 30 min= 9/2
t = d/s
d/15 + d/30 = 9/2 so distance =45 km
time required for for 45 km is
45/15 = 3 hrs
45/30 = 1.5 hrs
so 3 + 1.5 = 4.5 ( 4 hrs 30 min) -----/ proved

Is this solution Helpfull? Yes (3) | No   

ANUJ JAIN  (10 years ago)

5 km/hr.

Let the speed of the stream be x km/hr. Then,

Speed downstream = (15 + x) km/hr,
Speed upstream = (15 - x) km/hr.
Therefore,
30/(15+x) + 30/(15-x) = 4(1/2)
=> 900/(225-x^2) = 9/2
=> 9x^2 = 225
=> x^2 = 25
=> x = 5

Is this solution Helpfull? Yes (2) | No (1)  

k.swati singh  (8 years ago)

Let the speed of the stream be x km/hr. Then,

Speed downstream = (15 + x) km/hr,

Speed upstream = (15 - x) km/hr.

30 + 30 = 4 1
(15 + x) (15 - x) 2
900 = 9
225 - x2 2
9x2 = 225

x2 = 25

x = 5 km/hr.

Is this solution Helpfull? Yes (2) | No   

naresh vadal;a  (11 years ago)

The question might be wrong if it is 30km distance then the answer 5km/hr could be the answer

Is this solution Helpfull? Yes (1) | No   

ashutosh shukla  (11 years ago)

if speed of stream is 15 kmph(i.e 30 -15 =15 kmph)then it relative velocity of boat with respect to stream will be zero("0"),so it will not come back .

Is this solution Helpfull? Yes | No (1)  

chakri  (7 years ago)

let speed of boat=a
speed of stream=b
now we have a=DOWNSTREAM+UPSTREAM/2
b=DOWNSTREAM-UPSTREAM/2
in question we have asked stream speed
threrefore b=DS-US/2=30-15/2=15/2=7.5
ans=7.5

Is this solution Helpfull? Yes | No   

Raghavendar  (7 years ago)

speed of the boat = 15 kmph
speed of the boat stiill in water means ( speed of the boat + speed of the stream ) = 30 kmph
therefore, speed of the stream = (speed of boat+ speed of stream ) - speed of boat
i.e..,, 30-15 = 15kmph.

Is this solution Helpfull? Yes | No (1)  

Chandan Kalia  (7 years ago)

Explanation:
Let the speed of the stream be x km/hr. Then,
Speed downstream = (15 + x) km/hr,
Speed upstream = (15 - x) km/hr

So we know from question that it took 4(1/2)hrs to travel back to same point.

So,
3015+x−3015−x=412=>900225−x2=92=>9x2=225=>x=5km/hr
3015+x−3015−x=412=>900225−x2=92=>9x2=225=>x=5km/hr

Is this solution Helpfull? Yes | No   

Please Login to Read Solution.