WAEC WAEC Nigeria General Mathematics

Revision Notes

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(Ratio, Proportion and Rates)

Ratio Applications

Understanding Ratio Applications

What Are Ratios?

A ratio is a way to compare two or more quantities. It tells us how much of one thing there is compared to another. Ratios can be written in three different ways:

  • Using a colon: 3:2
  • As a fraction: 32\frac{3}{2}
  • In words: 3 to 2

Using Ratios in Real Life

Ratios are used in various real-life situations, such as:

  • Cooking: Recipes often use ratios to ensure the right balance of ingredients.
  • Maps: Scale ratios help us understand distances on maps.
  • Mixing: Ratios are used to mix paints or chemicals in specific proportions.

Proportion and Similar Ratios

Proportion means that two ratios are equal. For example, if ab=cd\frac{a}{b} = \frac{c}{d}, then a,b,c,a, b, c, and dd are in proportion.

When comparing similar ratios, we can find unknown values using cross-multiplication.

Worked Example

Example: If 23=x9\frac{2}{3} = \frac{x}{9}, find xx.

Rates

A rate is a special type of ratio where two quantities with different units are compared. For example, speed is a rate that compares distance to time, like 60 km/h.

Solving Rate Problems

To solve rate problems, use the formula:

Rate=DistanceTime\text{Rate} = \frac{\text{Distance}}{\text{Time}}

Worked Example

Example: A car travels 150 km in 3 hours. What is its speed?

Tuity Tip

Hover me!

Tuity Tip: Always check that your units match when working with rates. Convert units if necessary to ensure consistency.

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