# Quantity Calculation

Many calculations in life involve direct relationships between quantities and measurements such as cost, length, weight or volume.

This means that when the quantity goes up, the measurement goes up in proportion to it.

Calculations involving direct relationships usually involve multiplication.

### Example

A carpet firm charges $$\pounds57$$ to fit a carpet. The carpet is priced at $$\pounds5.24$$ per square metre. What is the total cost of buying $$24m^{2}$$ of carpet and having it fitted?

Cost of carpet $$= \pounds5.24 \times 24m^{2} = \pounds 125.76$$

Total cost $$= \pounds125.76 + \pounds57 = \pounds182.76$$

Question

A lorry when empty weighs $$1\,256\,kg$$. It is to be loaded with boxes each weighing $$84.3kg$$

What will be the total weight of the lorry and load if 18 boxes are to be transported?

Weight of boxes $$=84.3\,\times\,18=1517.4kg$$

Total weight $$= 1517.4 + 1256 = 2773.4kg$$