algebra readiness lesson 7-3 warm up lesson 7-3 warm-up
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ALGEBRA READINESS
LESSON 7-3Warm Up Lesson 7-3 Warm-Up
ALGEBRA READINESS
LESSON 7-3Warm Up Lesson 7-3 Warm-Up
ALGEBRA READINESS
“Percents and Proportions” (7-3)
How do you find the percent of a number?
Method 3: Proportion
55
1
So 22% of 250 is 55
# %
Known (Part) x 22
Unknown (Whole) 250 100
= Proportion .x
25022
100
100 • x = 250 • 22 Cross products are equal.
100x = 5500 Simplify.
= Divide both sides by 100. .5500100
1
1
x = 55 Simplify.
ALGEBRA READINESS
Use a proportion to find 60% of 45.
100 • n = 60 • 45 Write the cross products.
100n = 2,700 Simplify.
n = 27 Simplify.
n45
60100= Write a proportion.
100n 100
2,700 100= Isolate the variable.
Use the Division Property of Equality.
Percents and ProportionsLESSON 7-3
Additional Examples
# %
Known (Part) x 60
Unknown (Whole) 45 100
27
1
1
1
ALGEBRA READINESS
Suppose 11,550 students make up 14% of a
city’s population. What is the population of the city?
A diagram can help you understand the problem.
11,500w
14100
= Write a proportion.
11,550 • 100 = 14w Write the cross products.
= Isolate the variable. Use theDivision Property of Equality.
1,155,00014
14w14
82,500 = w Simplify.
Percents and ProportionsLESSON 7-3
Additional Examples
# %
Known (Part) 11,550 14
Unknown (Whole) w 100
82,500
1
1
1
ALGEBRA READINESS
(continued)
The population of the city is 82,500 people.
Check for Reasonableness: 82,500 is about 80,000. Because14% of 80,000 is 8,000 (10%) + 800 (1%) + 800 (1%) + 800 (1%) + 800 (1%) = 11,200, which is close to 11,155, the answer is reasonable.
Percents and ProportionsLESSON 7-3
Additional Examples
ALGEBRA READINESS
26 is what percent of 80?
26 is 32.5% of 80.
26 • 100 = 80p Write the cross products.
2,600 = 80p Simplify.
32.5 = p Simplify.
80p 80
2,600 80 = Use the Division Property of Equality.
to isolate the variable
2680
p100= Write a proportion.
A diagram can help youunderstand the problem.
Percents and ProportionsLESSON 7-3
Additional Examples
# %
Known (Part) 26 p
Unknown (Whole) 80 100
1
1
ALGEBRA READINESS
1. Find 25% of 160.
2. 45 is 75% of what number?
3. Find what percent 68 is of 80.
40
85%
60
Percents and ProportionsLESSON 7-3
Lesson Quiz