A ratio can be worked out if the fraction of the whole is known.

The denominator gives the total amount. The numerator gives the amount of each part.

In a class of 32 students, `frac(1)(4)` of them wear glasses. What is the ratio of wearers : non-wearers?

The fractions of wearers `frac(1)(4)`.

The fraction of non-wearers is 1 - `frac(1)``frac(4)` = `frac(3)(4)`.

Compare the numerators for the ratio 1:3.

Answer: 1:3

There are 24 cars in a car park. `frac(1)(4)` are red, and `frac(1)(6)` are silver. The remaining cars are blue. What is the ratio of red:silver:blue cars in the car park?

Find equivalent fractions with the same denominator.

Red cars: `frac(1)(4)` = `frac(6)(24)`

Silver cars: `frac(1)(6)` = `frac(4)(24)`

There are 14 cars remaining (24 - 6 - 4) = `frac(14)(24)`

Compare the numerators 6:4:14, and simplify to 3:2:7.

(Note that there could be more than 24 cars, but the number of cars must be a multiple of 24 and the fractions and ratios would remain the same)

Answer: 3 : 2 : 7

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