Ratio, Proportion, Percen

Ratios, Proportions, and Percent

By Amy Dougherty

​Ratios are used to compare two quantities.

Can be written in colon form:

a : b

​Or

In fraction form:

a
b

​Ratios should be simplified just like fractions

Multiple Choice

Select the correct ratio:

A soccer team won 10 games and lost 6 games

• $$\ \frac{6\ losses}{10\ games}$$

• $$\frac{10\ wins}{16\ games}$$

• $$\ \frac{10\ games}{16\ losses}$$

• $$\frac{6\ wins}{10\ losses}$$

Match

Match the ratio to its simplest form

• 8 : 12

• 18 : 6

• 60 : 70

• 3 : 12

• 9 : 24

2 : 3

3 : 1

6 : 7

1 : 4

3 : 8

• 2 : 3

• 3 : 1

• 6 : 7

• 1 : 4

• 3 : 8

​Proportions

​A proportion shows two equal ratios in the form of an equation.

Use cross multiplication to create an equation and solve for "X"

Multiple Choice

Which is the correct proportion to solve this problem?

Ashley read 80 pages of her book in 64 minutes. Later she read for 20 minutes. If she read at that same rate, how many pages did she read?

• $$\frac{80}{64}=\frac{x}{20}$$

• $$\frac{64}{20\ }=\frac{x}{80}$$

• $$\frac{80}{100}=\frac{x}{20}$$

• $$\frac{20}{100}=\frac{64}{x}$$

Drag and Drop

What are the two units being compared for the ratio?

A recipe calls for 2 cups of flour to make a batch of 35 cookies.

It is comparing ​

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.

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cups of flour to cookies

grams of sugar to muffins

liters of water to cakes

tablespoons of butter to brownies

Match

Match what is being compared in each problem

• A lion eats 168 lbs of food in 3 weeks

• A circle with a diameter of 20 units has a circumference of 62.8 units

• There are 2 adults for every 3 children in Sunday School

• A bus used 2 gallons of gas to travel 25 miles.

• She played chess 20 times and won 12 games

• $$\frac{lbs}{weeks}$$

• $$\frac{diameter}{circumference}$$

• $$\frac{adults}{children}$$

• $$\frac{gallons}{miles}$$

• $$\frac{games}{wins}$$

Percents

a percent is a part to whole ratio, where the WHOLE is always 100


Percent problems can be found by creating proportions

Drag and Drop

Which proportions could John use to answer this problem?

What is 36% of 150

​

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​Percent of Change

​Describes the change over time either by an increase or a decrease

​%

100

CHANGE

ORIGINAL

​=

​Percent Error

​Find the absolute error by subtracting the estimated amount by the actual amount

​%

100

​=

​absolute error

actual amount

Match

Match the absolute error:

• The weight measured was 56g but the actual weight was 53g

• The temperature recorded was 22°C but the actual temperature was 20°C

• The length measured was 150cm but the actual length was 145cm

• The speed indicated was 80km/h but the actual speed was 75km/h

• The volume measured was 2L but the actual volume was 1.8L

3g

2°C

5cm

5km/h

0.2L

• 3g

• 2°C

• 5cm

• 5km/h

• 0.2L

​Simple Interest

​I = interest (money earned)
p= principal (money in the bank)
r = rate (percent)
t= time (in years

Formula to find interest:

I = prt

Match

Identify the numbers for each part of the simple interest formula.

A deposit of $900 for 20 years at a simple interest rate of 4%.

• Interest

• Principal

• Rate

• Time

• Total Value

$720

$900

0.04

20

$1,620

• $720

• $900

• 0.04

• 20

• $1,620