PERCENT
"Percent % " means
"per 100" or 'out of 100' or ‘per 100 of the total value’.
->
the first quantity usually represents a part of, or a
change in, the second quantity.
Defining Percent
Percent means “per 100” =>
60%
= 60 / 100
25%
= 25 / 100
Example:
What is 1 per
100 as a percent?
1 per 100 means ‘1 out
of 100’ -> 1 is 1% out of a total value of 100
-> 1%
Relating to Fractions:
=> Part/Whole x 100 = %
Diagram illustration:
Examples
(a) What is the
25 per 100 in percent?
25 per 100
-> 25%
Diagram illustration:
(b) What is the percent of
100 out of 100?
100 per 100 -> 100%
Using Percentage
We can use percentage to help us:
(1) Compare 1 quantity with another.
Duracell
battery last 35% longer as compared to the next competing batteries
(2) Express how large or small one quantity to the total quantity
25% out of the full battery (out of 100%) is
left
(3) Express change(increase or decrease) of quantity in
relative to its original
quantity.
Calculating Percentage
Common sentence construct in Percent:
P as a percentage of Q -> OF VALUE.
The OF ‘VALUE’ is the Total Value -> it has a percent of 100% (or as stated)
Formula
Percent = Given Value x
100%
Total
Value
Value = Given percent x Total value
100%
Example:
Express 20 cm as a percentage of 250cm.
20cm as %, total= 250 Step1: Write numbers
Percent = Given Value x 100 Step2: Use/link, formula
Total Value
= 20 x 100
250
= 8% Step3: Calculate/Solve
Example
a. What is 40% of 80.
b. What is 150% of 80?
a. 40% , total = 80 Step1: Write numbers
= 40 x 80. Step2: Use/write formula
100
= 32 Step3: Solve
b. 150%, 80. Step1: Write 150% of number, 80
= 150 x 80 Step2: Use/write formula
100
= 120 Step3: Solve
One-percent Method
This method is to compute the value of 1%, and then
multiply it with the required value. It is similar to the cross-multiply method.
It provides a more detailed breakdown for easy understanding.
Example:
Express 50 cm as a percentage of 250cm
100% -> 250cm Step 1: Write numbers
100 % - > 250 Step 2: Use/link [ value of 1% ]
1% - > 250 / 100
1% -> 2.5cm
50cm -> 50 / 2.5 (per 2.5 -> divide). Step3: Solve
= 20%
Converting Percent to Fractions
Percent can be expressed as #/100
29%
is 29/100 (29/100 is a fraction)
Example
Convert 15% to fraction.
Method
Step1: Express
percent as #/100
15% = 15/100
Step2:
Simplify fraction to lowest term
= 15 3 /100 20
= 3 / 20
Example:
(1) 0% = 0/100
= 0
(2) 100% = 100/100
= 1
(3) 120% = 100/100 + 20 1 /100
5
=
1 + 1/5
=
1 1/5
Converting Fractions to Percent
Example:
Express 1/2 as
percentage
Step 1: Multiply by 100
½
x 100 = 50
Step 2: Express the fraction as percent
1/2 as percent is 50%
Example:
Express 3/4 as a percentage
Step 1: Multiply by 100
¾
x 100 = 75
Step 2: Express the fraction as percent
¾
as percent is 75%
Converting Percent to Decimal
Example
Express 26% as a decimal.
Method:
Step1: Change % to #/100
26%
- > 26/100
Step2: Change 2/100 to 0.#
26/100
= 0.26
Example
Express
37% as a decimal.
Method:
Step1: Insert decimal point (if required)
37%
= 37.0%
Step2: Shift decimal 2 places to the left
37.0%
= 0.37
Converting Decimals to Percent
Example
Convert 0.345 to percent
Method
Step: Move Decimal point 2 places to the right
0.345
= 0.0345 x 100% = 34.5%
SUMMARY
Expressing
Percentages as Fractions and Decimals
Percentage
|
÷ 100
|
Fractions
|
Decimals
|
8%
|
8 ÷100 = 8 / 100
|
2/25
|
0.08
|
25%
|
25 ÷ 100 = 25 / 100
|
1/4
|
0.25
|
30%
|
30 ÷ 100 = 30 / 100
|
3/10
|
0.3
|
50%
|
50÷ 100 = 30 / 100
|
1/2
|
0.5
|
62.5%
|
62.5 ÷ 100 = 625 / 1000
|
5/8
|
0.625
|
75%
|
75 ÷100 = 75 / 100
|
3/4
|
0.75
|
80%
|
80 ÷ 100 = 80 / 100
|
4/5
|
0.8
|
97.5%
|
97.5 ÷ 100 = 975 / 1000
|
39/40
|
0.975
|
~~~~ END ~~~~ :)
VIDEOS
Solving Percentage Question : using the 1% method
Solving Percentage Question : Using Model
25% out of the full battery (out of 100%) is
left
