Question

two pipes p1 and p2 can fill a tank in 20 minutes and 30 minutes respectively. Both the pipes were opened together when the tank was empty but the pipe p2 was closed after 2 minutes. How long will it take for the pipe p1 to fill the remaining part of the tank ?

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Answer 1

Answer:

In 1 mt p1 will fill 1/20 part of tank

In 1 mt p2 will fill 1/30 pay of tank

So in 2 mt (2/20 + 2/30) = 1/6 part of tank will be filled

Remaining part of tank = 1 - (1/6)=5/6 part of tank has to be filled by p1

whole part (=1) of the tank is filled by p1 in 20mt

5/6 part of tank will be filled by p1 in 20×5/6 mt =50/3 mts