Latest CAT Aptitude Question SOLUTION: Two pipes a and b can separetly fill a cistern in 60min and 75min respectively. there is a third pipe in the bottom of the cistern to empty it. if all the three pipes are simultane

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(#M40034675) CAT Numerical Ability question pipes and cisterns Keep an EYE

Two pipes a and b can separetly fill a cistern in 60min and 75min respectively. there is a third pipe in the bottom of the cistern to empty it. if all the three pipes are simultaneously opened, then the cistern is full in 50min. in how much time the third pipe alone can empty the cistern?

Asked In CAT ramakrishna (10 years ago)

Solved Saraswathy Read Solution (4)

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Read Solution (4) :

Saraswathy  (10 years ago)

a's 1 min work = 1/60
b's 1 min work = 1/75
Let 3rd pipe's 1 hr work = 1/x

in 50 mins , it ll be full if all r opened
So in 1 min 1/50 part of d tank is filled

1/60 + 1/75 -1/x = 1/50
1/x = 1/60 + 1/75 -1/50
1/x = 5 + 4 - 6/300 = 3/300 = 1/100

In 1 min , 3rd pipe ll empty 1/100 part of the tank
So it ll empty d fll tank in 100 mins

Ans : 100min

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Ann Theressa  (10 years ago)

100 min

Let x be the time taken by 3rd pipe to empty the cistern
Together they fill the cistern in 50 min
===>
1/60+1/75-1/x = 1/50
1/x = 3/100 - 1/50
=1/100
===>x = 100 min

3rd pipe can empty cistern in 100min

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sravani  (9 years ago)

given a+b-c=1/50(since c is empting the tank)
so,1/60 + 1/75 -c = 1/50
c=1/60 + 1/75 - 1/50
=1/100
so,c completly empties the tank
in 100 mins...

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soumi sen  (10 years ago)

a and b fills in 1 min= 1/60+1/75=3/100 portion
let c empties the cistern in C min
so in 1 min c empties 1/C portion
in 1 min cistern is filled=3/100-1/C
now, 3/100-1/C=1/50
C=100min

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