How_To_Be_Good_At_Math

74 NUMBERS •^ DIFFERENT WAYS TO DESCRIBE FRACTIONS

Fractions, decimals, and

percentages are all linked,

and we can express one

as any of the others.

Different ways to

describe fractions

Decimals and percentages are just different ways of

describing fractions. Ratio and proportion can be

written as fractions, too.

Proportion as a fraction,

a decimal, or a percentage

Look at these 20 roses. There are 12 pink and 8 red

roses. Let’s describe the proportion of pink roses as

a fraction, a decimal, and a percentage.

As a decimal

If we rewrite^3 ⁄ 5 as equivalent

tenths, we get^6 ⁄ 10 , which is the

same as 0.6. So, 0.6 of the group

consists of pink roses.

As a fraction

There are 12 pink roses out

of a total of 20 roses. So, the

proportion of pink roses is^12 ⁄ 20

or, if we simplify it,^3 ⁄ 5.

As a percentage

If we rewrite^6 ⁄ 10 as

hundredths, we get^60 ⁄ 100 , which

can also be written as 60%.

So, 60% of the roses are pink.

Ratio and fractions

On page 70, we learned how to write ratios using two dots

between the numbers. But we can write ratios as fractions, too.

We can also write this ratio

as^3 ⁄ 12 or^1 ⁄ 4 , which means

that the number of roses is a

quarter of the number of daisies.

Now we have three roses

and 12 daisies. We write the

ratio of roses to daisies as 3:12,

then simplify it to 1:4.

3

5

PROPORTION OF PINK ROSES

=

=

0.6 =

3 : 12 or 1 : 4

3

12

1

or 4

The first number in the ratio

becomes the fraction’s numerator

The second number in the ratio

becomes the fraction’s denominator

12 out of 20

roses are pink

60%

RATIO OF ROSES TO DAISIES

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