Pre-Algebra Chapter 6 - Ramsey School District

Example 4
Find the Part
What number is 5.5% of 650?
The percent is 5.5, and the base is 650. Let a represent the part.
a p
1 b 00 → a 5.5
Replace b with 650 and p with 5.5.
650
1 00
a · 100 650 · 5.5 Find the cross products.
100a 3575 Simplify.
a 35.75 Mentally divide each side by 100.
So, 5.5% of 650 is 35.75.
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usa_today
Example 5
Apply the Percent Proportion
CHORES Use the graphic to
determine how many of the USA TODAY Snapshots ®
1074 youths surveyed do not
clean their room because
Kids don’t enjoy cleaning their rooms
When 1,074 youths 19 and under were
there is not enough time.
asked why they don’t clean their room more
The total number of youths
is 1074. So, 1074 is the base.
The percent is 29%.
To find 29% of 1074, let b
represent the base, 1074, and
let p represent the percent,
29%, in the percent
often, these were their responses 1 :
I don’t like to
Not enough time
I’m too lazy
29%
28%
The rest of the
proportion. Let a represent
6%
house is dirty
the part.
a p
1 b 00 → No reply 2%
a 29
1 — More than one
1074
1 00
response allowed
a · 100 1074 · 29
100a 31146
Source: BSMG Worldwide
Simplify.
a 311.46 Mentally divide each side by 100.
So, about 311 youths do not clean their room because there is not
enough time.
66%
By Lori Joseph and Sam Ward, USA TODAY
Example 6
Find the Base
Fifty-two is 40% of what number?
The percent is 40% and the part is 52. Let b represent the base.
a p
1 b 00 → 5 2 40
1
b 00
Replace a with 52 and p with 40.
52 · 100 b · 40 Find the cross products.
5200 40b Simplify.
52 00
4 0b
40
40
Divide each side by 40.
130 b Simplify.
So, 52 is 40% of 130.
290 Chapter 6 Ratio, Proportion, and Percent