Question

A tank can be filled by a tap in 20 minutes and by another tap in 60 minutes. Both the taps are kept open for 10 minutes and then the first tap is shut off. After this, the tank will be completely filled in ​

Answer 1

Answer:

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Part of the tank filled by both the taps in 10 minutes

= 10 × (1/20 + 1/60) = (3 + 1/60) =2/3

Remaining part = 1 – 2/3 = 1/3

1/60th part of the tank is filled by the second pipe in 1 min.

Therefore, 1/3rd of the tank will be filled by the second pipe in 60 × 1/3 = 20 min.

Answer 2

Answer:

First tap => (1/20)*10 = 1/2

Second tap => (1/60)*10 = 1/6

Total work done = (1/2) + (1/6) = 3/6+1/6 = 4/6 = 2/3.

Remaining work = 1- (2/3) = 1/3.

Which is done by second tap in (1/3)*60 = 20 minutes.

Hope this helps! :)