Determine an unknown value using unitary method

Proportion

7.3

Proportion

We will learn to determine an unknown value using the unitary method.

Proportion is a comparison between two different quantities of units and is usually expressed as one quantity per unit of another quantity.
Rates can be found by dividing the two quantities involved.
The unit of rate measurement is the unit of numerator per unit of the denominator.

EXAMPLE:

A car can travel 350 km with 50 litres of petrol. How far would it be if the car was only filled with 20 litres of petrol?

SOLUTION:

50 litres = 350 km
20 litres = ___ km

\(\frac{350 \text{ km}}{50\text{ liter}}=\frac{?}{20\text{ liter}}\)

\(\frac{350}{50}\times{20}=140\)

20 litres = 140 km