ratio comparing 10 apples to 3 oranges


A comparison between two quantities (multitudes or magnitudes) of the same type, where we compare them in terms of their relative size.

For example:

The things being compared are called the “terms” of the ratio.

Ratios are written in the form “𝑎 : 𝑏 ” for the two quantities (“terms”) being compared.

The first term, 𝑎, is called the antecedent term, and the second term, 𝑏, is called the consequent term.

The convention for writing ratios uses:

Related terms: rational number, irrational number

Why Ratios Matter

A ratio is a comparison that takes place in the mind.

But they describe very real relationships between things in the world.

The ratio of your income to your expenses, is the difference between saving money or being driven into debt.

The ratio of deaths from a disease to people infected (with the disease), tells you how deadly the disease is.

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