#### Answer

The capacity of a pail used to wash floors is approximately 12 L.

#### Work Step by Step

We know that $1~L = 1000~mL = 1000~cm^3$
If a box had a base of 20 cm by 20 cm and a height of 10 cm, then the volume would be $4000~cm^3$. This would give the box a capacity of 4 L. Since a height of 10 cm is too short for a pail, an estimate of 3 L for a pail seems too small.
If a box had a base of 20 cm by 20 cm and a height of 30 cm, then the volume would be $12,000~cm^3$. This would give the box a capacity of 12 L. Since these dimensions seem similar to a pail, an estimate of 12 L for the capacity of a pail seems reasonable.
If a pail had a capacity of 80 L, this would be enough water to fill 80 one-liter bottles. Clearly, this is too much for a normal pail of water.
If a pail had a capacity of 2 kL, this would be enough water to fill 2000 one-liter bottles. Clearly, this is too much for a normal pail of water.
The capacity of a pail used to wash floors is approximately 12 L.