A cistern is filled by pipe A in 10 hours and the full cistern can be leaked out by an exhaust pipe B in 12 hours. If both the pipes are opened, in what time the cistern is full?
Work done by the inlet in 1 hour: = 1/10
Work done by the outlet in 1 hour = 1/12
Net part filled in 1 hour = [ 1/10 – 1/12 ] = 1/60
The cistern will be full in 60 hours.
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