A tap can fill a cistern in 8 hours and another can empty

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A tap can fill a cistern in 8 hours and another can empty it in 16 hours. If both the taps are opened simultaneously, the time (in hours) to fill the tank is ?

1. 8
2. 10
3. 16
4. 24

Correct Option: C

Part filled by intel in 1 hour = 1/8
Part emptied by outlet in 1 hour = 1/16
Net filling in 1 hour = (1/8 - 1/16) = 1/16
∴ Time taken to fill the tank = 16 hours