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Finding Percent of Change
Finding Percent of Change
Percent of Change
Percent of Change
Finding the Percent of Change
Finding the Percent of Change
Percent of Change – the percent a quantity increases or
decreases from the original amountStep 1 – Subtract to find the amount of changeStep 2 – Use the proportion
Amount of change = Percent of change Original amount 100
Percent of Change - Increase
Percent of Change - Increase
Finding the Percent of Increase
Finding the Percent of Increase
North Carolina had 12 seats in the U.S. House of Representatives in the 1990’s. After the 2000 census, North Carolina had 13 seats. Find the percent of increase in the number of representatives.
Step 1 – Subtract to find the amount of change
13 seats - 12 seats = 1 seat change
Finding the Percent of Increase
Finding the Percent of Increase
Step 2 – Use the proportion
Amount of change = Percent of change Original amount 100 1= x 12 100
1 (100)
= 12 x10
0= 12
x1212
8.3%
= x
Finding the Percent of Increase
Finding the Percent of Increase
A restaurant worker earning $5.15 an hour receives a raise. He now earns $6.00 and hour. Find the percent of increase in his hourly rate of pay.
Step 1 – Subtract to find the amount of change
$6.00 - $5.15 = $0.85 increase per hour
Finding the Percent of Increase
Finding the Percent of Increase
Step 2 – Use the proportion
Amount of change = Percent of change Original amount 100 $0.85 = x $5.15 100
0.85 (100)
= 5.15 x
85= 5.1
5 x5.15
5.1516.5%
= x
Finding the Percent of Increase
Finding the Percent of Increase
Vincent collects dinosaurs. Before his birthday he had 16 dinosaurs. After his birthday party, he had a total of 40 dinosaurs. Find the percent of increase in the number of dinosaurs Vincent has.
Finding the Percent of Increase
Finding the Percent of Increase
40 - 16 = 24 dinosaurs
Amount of change = Percent of change Original amount 100 24= x 16 100
24 (100)
= 16 x
2400
= 16 x16
16150%
= x
Percent of Change: Decrease (discount)
Percent of Change: Decrease (discount)
Finding the Percent of Decrease
Finding the Percent of Decrease
During a clearance sale, a keyboard that normally sells for $49.99 is discounted to $34.99. What is the percent of discount?Step 1 – Subtract to find the amount of change
$49.99 - $34.99 = $15.00 discount
Finding the Percent of Decrease
Finding the Percent of Decrease
Step 2 – Use the proportion
Amount of change = Percent of change Original amount 100 $15.00 = x $49.99 100
15 (100)
= 49.99 x15
00= 49.9
9 x49.99
49.9930%
= x
Finding the Percent of Decrease
Finding the Percent of Decrease
Due to the number of infractions given, the number of students able to attend the Mardi Gras Mania decreased from 206 students to 180 students. What is the percent of decrease?
Finding the Percent of Decrease
Finding the Percent of Decrease
206 - 180 = 26 students
Amount of change = Percent of change Original amount 100 26= x 206 100
26 (100)
= 206 x
2600
= 206 x206
20612.62%
= x
Percent of Change: Markup
Percent of Change: Markup
Finding the Percent of Markup
Finding the Percent of Markup
An electronic store orders sets of walkie-talkies for $14.85 each. The store sells each set for $19.90. What is the percent of markup?Step 1 – Subtract to find the amount of markup
$19.90 - $14.85 = $5.05 markup
Finding the Percent of Markup
Finding the Percent of Markup
Step 2 – Use the proportion
Amount of markup = Percent of change Original cost 100 $5.05 = x $14.85 100
5.05 (100)
= 14.85 x50
5= 14.8
5 x14.85
14.8534%
= x
Finding the Percent of Markup
Finding the Percent of Markup
Macy’s spends $30.72 on Polo shirts. They then sell the shirt for $55.84. What is the percent of markup on the Polo shirts?
Finding the Percent of Markup
Finding the Percent of Markup
$55.84 - $30.72 = $25.12
Amount of markup = Percent of change Original cost 100 25.12 = x 30.72 100
25.12 (100)
= 30.72 x
2512
= 30.72 x30.72
30.7281.77%
= x
Finding the Original
Finding the Original
Finding the OriginalFinding the Original How do we find the
original price when we know the discounted price and the percent off? Watch Example Video
Finding the OriginalFinding the Original Step one – Find the
percentage you are paying by subtracting 100% - the percent off Step two – divide the discounted price by the percent you are paying
Finding the OriginalFinding the Original A shirt is on sale for 40% off. The sale price is $12. What is the original cost of the shirt? Step 1: 100% - percent off = percent still paying for
100% - 40% = 60%
Step 2: sale price ÷ % paying for = original price
12 ÷ .60 = $20.00
Finding the OriginalFinding the Original A television is on sale for 30% off. The sale price is $425. What is the original cost of the television? Step 1: 100% - percent off = percent still paying for
100% - 30% = 70%
Step 2: sale price ÷ % paying for = original price
425 ÷ .70 = $607.14
Finding the OriginalFinding the Original
Step 1: 100% - percent off = percent still paying for
100% - 20% = 80%
Step 2: sale price ÷ % paying for = original price
$12,375 ÷ .80 = $15,468.75
A car is on sale for 20% off. The sale price is $12,375. What is the original cost of the car?
Homework Time! Luck of the Irish
To You!
Homework Time! Luck of the Irish
To You!