There is a leak in the bottom of a cistern. when the cistern is thoroughly repaired,it would be filled in 12 minutes.it now takes 18 min longer.if the cistern is full,how long would the leak take to empty the cistern
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Time taken to fill repaired cistern = 12 mins
In 1 min, pipe will fill = 1/12
Time taken to fill cistern with leak = 12 + 18 = 30 mins
In 1 min, it will fill = 1/30
Consider the leak as an outlet pipe, so
1/30 = 1/12 - [ in 1 min how much the outlet pipe leaks ]
= 1/12 - 1/30
= 5/60 - 2/60 = 3/60 = 1/20
Therefore, it will take 20 mins for the leak to empty the cistern.
In 1 min, pipe will fill = 1/12
Time taken to fill cistern with leak = 12 + 18 = 30 mins
In 1 min, it will fill = 1/30
Consider the leak as an outlet pipe, so
1/30 = 1/12 - [ in 1 min how much the outlet pipe leaks ]
= 1/12 - 1/30
= 5/60 - 2/60 = 3/60 = 1/20
Therefore, it will take 20 mins for the leak to empty the cistern.
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