5 Minute Check
Complete on the back of your homework.
1. Find 6% of 95.
2. Find 28% of 575.
3. Find 0.6% of 36.
4. Find 0.03% of 1500.
5 Minute Check
Find 6 % of 95.
95
x .06
570
0000
5.70
5 Minute Check
Find 28 % of 575.
5 Minute Check
Find 28 % of 575.
28
100
7
25
=
=
?
575
?
575
7x575=3500+490+35=4025÷25=161
5 Minute Check
Find 28 % of 575.
575
x .28
4600
11500
161.00
5 Minute Check
Find 0.6 % of 36.
5 Minute Check
Find 0.6 % of 36.
0.6
100
=
?
36
36
x .6
21.6
0 decimals
1 decimal
1 decimal
0.6 x36 = 21.6 ÷100 =0.216
5 Minute Check
Find 0.6 % of 36.
.006
x 36
36
180
.216
5 Minute Check
Find 0.03 % of 1500.
5 Minute Check
Find 0.03 % of 1500.
0.03
100
?
1500
=
1500
x .03
45.00
0 decimals
2 decimals
2 decimals
0.03 x1500 = 45 ÷100 = 0.45
5 Minute Check
Find 0.03 % of 1500.
1500
x .0003
4500
00000
.45
Binder
Organization
Tuesday, Sept 16
Lesson 6.2.8
Solve Percent Problems
Solve Percent Problems
Objective: To solve percent problems which
involve finding the whole or part.
Solve Percent Problems
The method to find a percent of a number
uses a proportion.
A proportion is when two fractions are
equivalent.
3
4
=
75
100
Solve Percent Problems
10 is 25% of what number?
Solve Percent Problems
10 is 25% of what number?
In other words,
25% of what number is 10, or
25% of ? is 10
Solve Percent Problems
10 is 25% of what number?
If 25% of what number is 10, will that what
number be bigger or smaller than 10?
Solve Percent Problems
10 is 25% of what number?
Yesterday when we found 25% of 10 the
proportion was:
25
?
100
10
=
Notice the small number is on top.
Solve Percent Problems
10 is 25% of what number?
Since we know the answer to the above
question will be bigger than 10, then the
proportion is:
25
10
100
?
Notice the small numbers are still on top, since
we determined the answer would be bigger
than 10.
=
Solve Percent Problems
10 is 25% of what number?
The method to solve these types of problems
is the same as the method we learned
yesterday, only the unknown will be in the
denominator of the 2nd fraction.
Solve Percent Problems
10 is 25% of what number?
parts
25
10
100
?
wholes
To Solve Percent Problems
Step 1 – Set up the proportion, with the
“parts” on top and the “wholes” on the
bottom.
=
Solve Percent Problems
10 is 25% of what number?
1
4
=
10
?
To Solve Percent Problems
Step 2 – Simplify, if possible.
Solve Percent Problems
10 is 25% of what number?
1
4
=
10
?
To Solve Percent Problems
Step 3 – Cross multiply and divide.
4 x 10 = 40 ÷ 1 = 40
Solve Percent Problems
30 is 50% of what number?
Step 1?
Solve Percent Problems
30 is 50% of what number?
50
100
=
Step 2?
30
?
Solve Percent Problems
30 is 50% of what number?
1
2
=
30
?
Step 3 ?
Solve Percent Problems
30 is 50% of what number?
1
2
=
30
?
2 x 30 = 60 ÷ 1 = 60
Solve Percent Problems
30 is 50% of what number?
x?
1
30
2
?
=
But, before you use this method try and find a
“multiplier” or “divider”.
Solve Percent Problems
90 is 75% of what number?
Step 1 ?
Solve Percent Problems
90 is 75% of what number?
75
100
=
Step 2 ?
90
?
Solve Percent Problems
90 is 75% of what number?
75
90
100 = ?
3
4
=
90
?
Step 3?
Solve Percent Problems
90 is 75% of what number?
75
90
100 = ?
3
4
=
90
?
4 x 90 = 360 ÷ 3 = 120, or you might have
noticed……
Solve Percent Problems
90 is 75% of what number?
75
90
100 = ?
3
4
x 30
=
90
?
Solve Percent Problems
60 is 20% of what number?
Do this on your own.
Solve Percent Problems
60 is 20% of what number?
20
60
100 = ?
1
5
=
60
?
5 x 60 = 300 ÷ 1 = 300
Solve Percent Problems
60 is 20% of what number?
20
100
x3
=
x3
60
300
Solve Percent Problems
10 is 40% of what number?
(Do this on your own)
Solve Percent Problems
10 is 40% of what number?
40
10
100
?
=
2
5
=
10
?
5 x 10 = 50 ÷ 2 = 25
Solve Percent Problems
10 is 40% of what number?
40
100
÷4
=
÷4
10
25
If you got 4, what did you do?
Solve Percent Problems
10 is 40% of what number? 25
You probably set up your proportion
incorrectly,(10 on bottom instead of on top)
Solve Percent Problems
What number is 40% of 60?
(Do this on your own)
Solve Percent Problems
What number is 40% of 60?
40
100
2
5
=
=
60
?
60
?
5 x 60 = 300 ÷ 2 = 150
Solve Percent Problems
What number is 40% of 60?
40
100
2
5
?
60
=
=
?
60
2 x 60 = 120 ÷ 5 = 24
Solve Percent Problems
What number is 40% of 60?
40
100
2
5
=
x 12
=
x 12
?
60
24
60
Solve Percent Problems
What percent of 120 is 120?
(Do this on your own)
Solve Percent Problems
What percent of 120 is 120?
?
100
?
100
=
120
120
=
120
120
Since the answer is a percent,
the ? must be in the “percent”
fraction (over 100).
100 x 120 = 1200 ÷ 120 = 100%
Solve Percent Problems
What percent of 600 is 12?
(Do this on your own)
Solve Percent Problems
What percent of 600 is 12?
?
100
?
100
=
12
600
=
1
50
2nd number in the question
1st number in the question
100 x 1 = 100 ÷ 50 = 2%
Solve Percent Problems
What percent of 600 is 12?
2
100
÷6
=
÷6
12
600
Solve Percent Problems
40 is 20% of what number?
(Do this on your own)
Solve Percent Problems
40 is 20% of what number?
20
100
x2
40
200
=
x2
Solve Percent Problems
40 is 20% of what number?
20
100
1
5
=
=
40
?
40
?
5 x 40 = 200 ÷ 1 = 200
Solve Percent Problems
What percent of 300 is 45?
(Do this on your own)
Solve Percent Problems
What percent of 300 is 45?
15
100
÷3
45
300
=
÷3
Solve Percent Problems
What percent of 300 is 45?
?
100
?
100
=
45
300
=
3
20
2nd number in the question
1st number in the question
100 x 3 = 300 ÷ 20 = 15
Solve Percent Problems
Molly has $10 in her wallet. If this is 20% of her
monthly allowance, what is her monthly
allowance?
(Do this on your own)
Solve Percent Problems
Molly has $10 in her wallet. If this is 20% of her
monthly allowance, what is her monthly
allowance?
20
100
÷2
=
÷2
10
50
Her monthly allowance is $50.
Solve Percent Problems
Molly has $10 in her wallet. If this is 20% of her
monthly allowance, what is her monthly allowance?
20
100
1
5
=
=
10
?
10
?
10 x 5 = 50 ÷ 1 = 50
Her monthly allowance is $50.
Solve Percent Problems
Before 1982 pennies were 95% zinc and 5% copper. If
100 pennies minted in 1980 have an approximate mass
of 15 grams of copper, what is the total mass of 100
pennies?
Do this on your own.
Solve Percent Problems
Before 1982 pennies were 95% zinc and 5%
copper. If 100 pennies minted in 1980 have
an approximate mass of 15 grams of copper,
what is the total mass of 100 pennies?
5
100
x3
=
x3
15
300
300 g. is the total mass
Solve Percent Problems
Before 1982 pennies were 95% zinc and 5% copper. If
100 pennies minted in 1980 have an approximate mass
of 15 grams of copper, what is the total mass of 100
pennies?
5
100
1
20
=
=
15
?
15
?
20 x 15 = 300 ÷ 1 = 300
Solve Percent Problems
Using what you know about percents, explain
why a commercial that says “80% of dentists
when asked used this toothpaste” might be
misleading.
Do this on your own.
Solve Percent Problems
Using what you know about percents, explain
why a commercial that says “80% of dentists
when asked used this toothpaste” might be
misleading.
You do not know how many dentists were
asked. It could have been 4 out of 5, or 80
out of 100, or 800 out of 1000.
Solve Percent Problems
The purity of gold is listed in karats. Refer to
the table. If a necklace is 75% gold, what
karat is it? Explain your reasoning.
Do this on your own.
Solve Percent Problems
The purity of gold is listed in karats. Refer to
the table. If a necklace is 75% gold, what
karat is it? Explain your reasoning.
18 karats; 24 is the whole
and 75 the percent.
75
100
=
18
24
Solve Percent Problems
Omar scored an 82% on his first test of the
quarter. Will a score of 38 out of 50 on the
second test help or hurt his grade? Explain
your reasoning.
Do this on your own.
Solve Percent Problems
Omar scored an 82% on his first test of the
quarter. Will a score of 38 out of 50 on the
second test help or hurt his grade? Explain
your reasoning.
38 out of 50 is 76%. Since that is less than his
first score, it will hurt his grade.
Solve Percent Problems
Agenda Notes
Homework –
Homework Practice 6.2.8
Circle your answers
Chapter 6.2 Test
Thursday, Sept 18
Accum Review 2 due Thursday, Sept 18