Latest Infosys Aptitude Question SOLUTION: Q. Two pipes a and b separately fill in 15/2 min and 5 min respactively and third pipe c can empty of 14l/m if all the pipes are open when the cistern is full, it is emptied in 1 h

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Q. Two pipes a and b separately fill in 15/2 min and 5 min respactively and third pipe c can empty of 14l/m if all the pipes are open when the cistern is full, it is emptied in 1 hr. how many litres does the cistern hold?

Asked In Infosys (10 years ago)

Solved mohan lal garg Read Solution (6)

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Read Solution (6) :

mohan lal garg  (10 years ago)

LET TOTAL WATER IN CISTERN=X LITER
SPEED OF A=2X/15 L/M (SPEED=LITER/TIME)
SPEED OF B=X/5 L/M
SPEED OF C=14 L/M
ACCORDING TO QUESTION

X+(X/5+2X/15)*60=60*14
X+=60*14
X=40 LITER

Is this solution Helpfull? Yes (45) | No (6)  

Ark Aditya  (10 years ago)

in 60 min. pipe a will fill the tank 8 times and pipe b 12 times.so in 1 hr the tank will be filled 8+12+1(already full at beginning)=21 times. so if capacity is X, 21X=14.60 , or X=40 capacity of tank

Is this solution Helpfull? Yes (16) | No (2)  

DHAKAD NEETENDRA SINGH  (10 years ago)

let capacity of cistern = x
a's speed= 2x/15 litre/min
b's speed= x/5 litre/min

a and b can fill in a minute= x[2/15 + 1/5]
= x/3 litre/min

but c can empty the full tank at the rate of 14 l/m
tank emptied in one minute= (x/3)-14= (x-14)/3 l/m

according to question
tank emptied in 1hr= 60 min
so,
(x-14)/3=1/60
x= 281/20

Is this solution Helpfull? Yes (7) | No (4)  

VanajaDevi  (10 years ago)

x+(x/5+2x/15)*60=60*14-I cant understand this step. please give me some more detailed explanation to this

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harshit gupta  (10 years ago)

Thank You Mohan Lal Garg

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

hercules  (2 years ago)

A fill cistern in one minute =1/15/2=2/15
B fill cistern in one minute =1/5
formula is -
work done by inlet pipe in 1min -work done by outlet pipe in 1 minute =(-1/60){because cistern emptied in one hour so in 1 min }
1/15/2+1/5 - (work done by outlet in 1minute = - 1/60
work done by outlet in 1 min = 2/15+1/5+1/60 =7/20
capacity of cistern= Flow rate in one min by waste pipe /work done by waste pipe in 1 min
=14/7/20=40 liters

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