Transcript MJ3 - Davidsen Middle School

MJ3
Ch 5.1 – Ratios & Percents
Bellwork
1. Express the ratio 6 cups to 3 quarts in
simplest form.
2. Express 400 meters in 16 minutes as a
unit rate.
3. A 10-foot wall casts a 15-foot shadow.
How tall is a nearby tree that casts a 45foot shadow?
Note: You do not have to write the
questions
Assignment Review
Before we begin….
 Please take out your notebook and get
ready to work….
 Building upon what we have learned
about ratios…today we will look at
percents, which is a type of ratio….
Objective
 Students will write ratios as percents
and vice versa.
Vocabulary
 Percent – A percent is a ratio that
compares a number to 100.
 Example
27 out of 100 can be written as
27 = 27%
100
 The symbol % means percent
Writing ratios as percents
 To write a ratio as a percent given a
verbal phrase, just place the number
over 100.
 Example – According to the 2000 U.S.
Census, 22 out of ever 100 people living
in West Virginia were younger than 18.
22 out of 100 = 22%
Your Turn
 In the notes section of you notebook
write the verbal phrases as percents.
1. During his baseball career, Babe Ruth
had a base hit about 34 out of every
100 times he came to bat.
2. In a recent year, 41.5 out of 100
households in the United States had
access to the Internet
Writing Ratios and Fractions as Percents
 You can write a ratio or fraction as a
percent by converting the ratio or
fraction to and equivalent fraction with a
denominator of 100
 Example:
1
=
20 =
20%
5
100
Your Turn
 In the notes section of your notebook
write the following as equivalent
fractions with a denominator of 100.
Then calculate the percent.
1. 3 out of 5
2. 1 out of 4
Using a Calculator



You can also use a calculator to calculate
percent.
Let’s do this together….
Using the fraction 9/20
1.
2.
3.
4.
Input the 9 into your calculator
Press the divide button
Input the 20 into the calculator
Press the % key….
Caution: If you press the = key you will have
to convert the number to a percent!
Your Turn
 Use you calculator to convert the
following ratios and fractions to a
percent
1. 3:5
2. 17:20
3. 17
50
Writing Percents as fractions
 You can write a percent as a fraction by
placing the percent over 100 and
simplifying.
 Example
30% =
30
=
3
100
10
24% =
24
=
6
100
25
Your Turn
 In the notes section of your notebook
write the following percents as
fractions in simplest form
1. 29%
2. 43%
3. 40%
Summary
 In the notes section of your notebook
summarize the key concepts covered in
today’s lesson
 Today we discussed
 Writing
ratios and fractions as percents
 Writing percents as fractions in simplest
form
Assignment
 Practice skills workbook lesson 5.1
 This assignment is due tomorrow
 You may use a calculator
 I will grade this assignment