Ratio practice

Ratio practice

Review for Quiz

Ratio

• Compares two or more quanties

• Can be written three ways       $a\ to\ b$   $a:b$   $\frac{a}{b}$  

• We should write them in simplest form when the compared values have common factors other than one.

Simplifying ratios

Look for the GCF then divide each value by that factor to put the ratio into simplest form.

Multiple Choice

What's the ratio of total shapes to triangles in simplest form?

• 15:2

• 13:2

• 7:1

• 1:6

Multiple Choice

What's the ratio of triangles to stars in simplest form?

• 3:2

• 6:4

• 2:3

• 4:6

Finding the missing value in a three way comparison

You should think about what you could multiply or divide by to get that missing value

Example of finding the missing value:

2:1:5 = 6:3:_

You know that you can multiply 2 by 3 to get 6, and 1 by 3 to get 3, so you must multiply 5 by 3 to get 15.

2:1:5 = 6:3:15

Word Problems

Start by drawing a model then use that to solve the problem

Mrs. Chin is shopping for Christmas presents for her family. The ratio of the price of present for her husband to the price of the present for her daughter is 7:1. What is the difference in prices of the two presents if Mrs. Chin spends $72 in all?

Model:

husband ∎∎∎∎∎∎∎

daughter ∎

All 8 units = $72

so, 8 units = $72

1 unit = $9

Therefore, the husband's gift was 7 x $9 = $63 and the the daughter was $9, so the difference is $63 - $9=$54