There are 500 learners in a school. Lunch time each learner takes one cup of tea. If the cup holds 50 cL, what is the volume of tea taken throughout the whole school in cm³?

Each learner takes 50 cL, and there are 500 learners.

$$\text{Total volume in cL} = 500 \text{ learners} \times 50 \text{ cL/learner}$$ $$\text{Total volume in cL} = 25000 \text{ cL}$$

We know that $1 \text{ L} = 100 \text{ cL}$.

$$\text{Total volume in L} = \frac{25000 \text{ cL}}{100 \text{ cL/L}}$$ $$\text{Total volume in L} = 250 \text{ L}$$

We know that $1 \text{ L} = 1000 \text{ cm}^3$.

$$\text{Total volume in cm}^3 = 250 \text{ L} \times 1000 \text{ cm}^3/\text{L}$$ $$\text{Total volume in cm}^3 = 250000 \text{ cm}^3$$

The volume of tea taken throughout the whole school is $\boxed{250000 \text{ cm}^3}$.

:
How many cubic centimetres make up a litre?

This is a standard conversion factor.

$$1 \text{ litre} = 1000 \text{ cubic centimetres}$$

$\boxed{1000 \text{ cm}^3}$ make up a litre.

:
5 jerrycans full of water weigh 109 kg. Each of the empty jerrycans weighs 1,800 g.
(The question is incomplete, but based on similar problems, we will find the mass of water in one jerrycan and its volume, and the mass of one full jerrycan.)

We know that $1 \text{ kg} = 1000 \text{ g}$.

$$\text{Mass of one empty jerrycan} = 1800 \text{ g} \times \frac{1 \text{ kg}}{1000 \text{ g}}$$ $$\text{Mass of one empty jerrycan} = 1.8 \text{ kg}$$

$$\text{Total mass of empty jerrycans} = 5 \times 1.8 \text{ kg}$$ $$\text{Total mass of empty jerrycans} = 9 \text{ kg}$$

$$\text{Total mass of water} = \text{Mass of 5 full jerrycans} - \text{Mass of 5 empty jerrycans}$$ $$\text{Total mass of water} = 109 \text{ kg} - 9 \text{ kg}$$ $$\text{Total mass of water} = 100 \text{ kg}$$

$$\text{Mass of water per jerrycan} = \frac{100 \text{ kg}}{5}$$ $$\text{Mass of water per jerrycan} = 20 \text{ kg}$$

Assuming the density of water is $1 \text{ kg/L}$:

$$\text{Volume of water per jerrycan} = 20 \text{ kg} \times \frac{1 \text{ L}}{1 \text{ kg}}$$ $$\text{Volume of water per jerrycan} = 20 \text{ L}$$

$$\text{Mass of one full jerrycan} = \text{Mass of one empty jerrycan} + \text{Mass of water per jerrycan}$$ $$\text{Mass of one full jerrycan} = 1.8 \text{ kg} + 20 \text{ kg}$$ $$\text{Mass of one full jerrycan} = 21.8 \text{ kg}$$

For :
Mass of water in one jerrycan: $\boxed{20 \text{ kg}}$
Volume of water in one jerrycan: $\boxed{20 \text{ L}}$
Mass of one full jerrycan: $\boxed{21.8 \text{ kg}}$