8:00 tuesday 4/24 ged math
DESCRIPTION
PercentTRANSCRIPT
AGENDA 4/24/12
• 1. Review: Conversions• 2. Finding the Part• 3. Finding the Percent• 4. Finding the Whole
REVIEW: CONVERSIONS
• Refer to Exercise 6
THE PERCENT STATEMENT
15% of $25 is $3.75Percent
Whole
Part
$3.75 is 15% of $25Part
Percent
Whole
You will be asked to find the part, the percent, or the whole.
𝑖𝑠𝑜𝑓
=%100
FINDING THE PART OF A WHOLE
• Two Strategies:• 1. Turn the percent into a decimal and then
multiply.
• Ex) Find 25% of 12.
• .25 x 12 = 3
• 3 is 25 % of 12.
PROPORTION AND PERCENT
𝑝𝑎𝑟𝑡h𝑤 𝑜𝑙𝑒
=%100 This relationship is ALWAYS TRUE.
𝑝𝑎𝑟𝑡h𝑤 𝑜𝑙𝑒
=%100
Josh got 4 out of 5 questions right on a test. What is his percentage?
45=%100
45=
𝒙100
Step 1: Write a proportion statement.
Step 2: Find the cross products.
𝒙
5 𝑥¿ 400Step 3: Divide by 5 on both sides.
5 5 𝑥=80%4 is the part.
5 is the whole.
We are looking for the %.
FINDING THE PART
• Find 25% of 12.
•Step 1: Set up a proportion.
•Step 2: Cross multiply.
•Step 3: Divide
FINDING THE PART• Option 2: Write a
proportion statement.
FINDING THE PERCENT
RULE• 1. First make a
fraction. Put the part (is) over the whole (of) and reduce.
• 2. Change the fraction to a percent.
EXAMPLE 3• 27 is what percent
of 45?
Casio fx-260 Calculator- Example 2
• Use the calculator to find what percent 27 is of 45.
AC1. Press
2. Press 2 7 5
The display should read 60.
÷ SHIFT4
The answer is 60%.
%
FINDING THE WHOLE
RULE• 1. Change the
percent to either a fraction or a decimal.
• 2. Divide the number by that fraction or decimal.
EXAMPLE 1• 20% of what is 9?
Casio fx-260 Calculator- Example 1
• Use the calculator to find 20% of what number is 9.
AC1. Press
2. Press 9 0
The display should read 45.
÷ SHIFT2 %
THE PERCENT CIRCLE
P
% x W
•P stands for the Part
•% stands for the Percent
•W stands for the WHOLE
•The horizontal line means divided by.
•The X means multipliedby
The Percent Circle
P
% x W
To Use the Percent Circle:
1. Cover the symbol of the number you are looking for.
2. Do the math shown by the uncovered symbols.
The Percent Circle
P
% x W
What is 50% of 8?
The Percent Circle
P
% x W
4 is 50% of what number?
Finding What Percent One Number is of Another
• To find a percent of a number:
• Step 1: Change the percent to a decimal or a fraction.
• Step 2: Multiply
• What is 62 ½ % of 56?
• Decimal• 62.5 x 56 = 3500
• Move decimal two places to the left.
• 62 ½ % of 56 is 35.
PART
• What is 62 ½ % of 56?• Fraction
• To find a percent of a number:
• Step 1: Change the percent to a decimal or a fraction.
• Step 2: Multiply
Change to a mixed number
Finding What Percent One Number is of Another
Finding What Percent One Number is of Another
• To find the part: • 1. First make a fraction.
Put the part over the whole and reduce.
• 2. Change the fraction to a percent.
• 27 is what percent of 45?
PERCENT
• The Melino family was on vacation for 12 days. It rained 3 of those days. On what percent of their vacation did it rain?
• Write the fraction as
• Change the fraction to percent.
•
Finding What Percent One Number is of Another
Finding a Number When a Percent is Given
• 1. Change the percent to either a fraction or a decimal.
• 2. Divide the number by that fraction or decimal.
• 20% of what number is 9?
• Change to a fraction
WHOLE
WORD PROBLEMS (PART)• A state official predicts that 70% of the registered voters in
Montana will vote on election day. If there are 514,000 registered voters in Montana, how many are predicted to vote?
Step 1: Understand the question. “How many registered voters are predicted to vote?”Step 2: What info do you need? Use the % of voters predicted to vote and the number of registered voters.Step 3: Choose the operation. What is 70% of 514,000?
EXAMPLE FROM P 135
• 6. Randi’s property tax bill is increasing by 3% this coming year. She now pays $890 a year in property tax.
• A) By how much is her property tax going to increase?
EXAMPLE FROM P. 135
• 6. Randi’s property tax bill is increasing by 3% this coming year. She now pays $890 a year in property tax.
• B) How much will she pay next year?