Ratios

Ratios

Mrs. Cantu

What is a ratio?

A ratio is a comparison of two numbers. It can be written three different ways.

Example: In a bag, there are 5 yellow marbles and 3 blue marbles.

Let's compare yellow to blue.

5 to 3

5:3

5/3

The order in which you write the ratio is important to the meaning.

Multiple Choice

Patrick has 2 black, 3 red, and 5 white toy cars. What is the ratio of red toy cars to all the toy cars?

• 3:5

• 1:3

• 3:11

• 3:10

Equivalent Ratios

• We can find equivalent ratios using multiplication or division

• Example 4:5, 8:10, 12:15

Turn and Talk

There are 2 red fish and 8 blue fish. The ratio of red fish to blue fish is 2:8. With your partner, determine two equivalent ratios.

Multiple Choice

Which ratio is equivalent to 5 to 4

• 25 to 20

• 10 to 12

• 4 to 5

• 15 to 8

Multiple Choice

Choose all ratios that are equivalent to 4 to 8.

• 1 to 2, 3 to 6

• 1 to 2

• 1 to 2, 12:15, 12 to 24

• 1 to 2, 3:6, 12:24

Compare the number of hammers to the number of nails.

• There are 3 hammers and 12 nails.

• The ratio of hammers to nails is 3 to 12, or 3/12

• 3/12 simplifies to 1/4. For every 1 hammer, there are 4 nails.

• There are 4 times as many nails as hammers

Open Ended

If there are 7 boys and 8 girls on the track team, what is the ratio of girls to boys? Write your answer three different ways.

Example

The ratio of boys to girls on a track team is 7 to 8. Write the ratio three different ways.

If there are 49 boys on the team, how many girls are there?

Open Ended

The ratio of boys to girls on a track team is 7 to 8. If there are 24 girls on the track team, how many boys are there?

Multiple Choice

If the ratio of boys to girls is 5:7, and there are 35 girls, how many boys are there?

• 30

• 25

• 5

• 10