How to calculate the storage time of bathtub

The calculation of the water storage time of the bathtub is as follows:

1. First, calculate the water output per minute of a faucet, which is 6 minutes more than that of an hour and a half, and the inflow of water is 4×6=24 (cubic meters), and the time is in minutes.

2. The water discharge per minute of a faucet is 24÷(5×15-8×9)=8 cubic meters, of which the inflow within 9 minutes is 4×9, and the water discharge per minute can be 8×13 if you turn on a faucet, excluding the inflow of 4 per minute.

3. The rest will release the original water, and it takes 54÷(8×13-4)=54 minutes to empty the original 54, so it takes 45 minutes for the whole bathtub to be filled with water.