Latest CAT Aptitude Question SOLUTION: Two pipes a and b can fill a tank in 15min and 20 min respectively. both the pipes are opended together but after 4 min.pipe a is turned off. what is the total time required to fil

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(#M40034677) CAT Numerical Ability question pipes and cisterns Keep an EYE

Two pipes a and b can fill a tank in 15min and 20 min respectively. both the pipes are opended together but after 4 min.pipe a is turned off. what is the total time required to fill the tank

Asked In CAT ramakrishna (10 years ago)

Solved Saraswathy Read Solution (3)

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Read Solution (3) :

Saraswathy  (10 years ago)

a's 1 min work = 1/15
b's 1 min work = 1/20

a+b's 1 min work = 1/15 + 1/20 = 35/ 300 = 7/60
a+b's 4 min work = 4 * 7/60 = 7/15

Remaining tank yet to be filled = 1-7/15 = 8/15

B ll fill
1 min ---- 1/20
x --------8/15
so 8/15*20 = 32/3 min

So totally 4 + 32/3 = 44/3 = 14 2/3 mins ===> 14mins 40 sec

Ans : 14 min 40 secs

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Neeraj Jain  (10 years ago)

a's 1 min work will be 4
b's 1 min work will be 3
Total work will be 60
Now a+b work for 4 min so total work done = 7*4=28
so work left=60-28==>32
Now time taken by b to complete remaining work=32/3
which is 10 min 40 sec and previouslly they worked for 4 min
So total time will be [14min 40sec]

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sravani  (9 years ago)

As both work for 4mins,work done by both for 4mins is 4(1/15 + 1/20)=28/60
Let X be the remaining time
only b worked for Xmin = (1/20)X
so, 28/60 + X/20 = 1
X/20=32/60
X=44/3 min = 14 min.40 secs.

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