Math 8 Chapter 5 Ratio Extra Notes.

A ratio is a comparison of quantities. We often hear statements about:

a team’s win-loss ratio the teacher-student ratio in a school the need to mix ingredients in a certain ratio or proportion:

These are all examples of ratios. Ratios are also commonly used to indicate the scales on maps and scale diagrams.

Getting started: Problem 1: Two-stroke fuel for a motor-bike is made by mixing 1 part oil with 7 parts petrol. How much oil and petrol is needed to fill a 20 litre tank?

Problem 2: A map has a 1: 1000 000 scale. Jen measures the distance between two towns on the map to be 9.8 cm. How far are the towns actually apart?

Writing Ratios as Fractions.

Equal Ratios.

PROPORTIONS

USING RATIOS TO DIVIDE QUANTITY.

SCALED DIAGRAM.