1. Simple Percent Problems
To solve a simple percent problem, you change the percent to a decimal and multiply.
Remember to move the decimal two places to the left.
Solve the following percent problems.

2. Other Percent Problems
For more involved percent problems, you use a ratio that compares a number to 100.
Let’s look at some actual problems.
At Summerville High School there are 553 freshmen, which is 35% of the total number of students. How many students attend the high school?
You need $2,500 to buy a car. You already have $1,575. What percentage of the amount that you need do you have now?
Don’t forget to write your answer as a percent.
There are a at total of 1,580 students at the high school.
You have 63% of the amount needed.

3. More Percent Problems That was easy What percent of 60 is 18?
15% of what number is 24?
8% of 125 is what number?
18 is 30% of 60
15% of 160 is 24
8% of 125 is 10
A jacket is on sale for 25% off. The original price is $
a) How much is the discount? b) How much is the sale price?
The sale price is $187.49
That was easy
The discount is $62.50

4. Simple Interest Formula
time
(in years)
principal
interest rate
interest
You deposit $50 in a savings account that earns 3.5% interest per year. How much interest will you earn after 3 years?
You deposit $840 in a savings account that earns 4.5% interest per year. How much interest will you earn after 4 years?
How much money in total will you have after 3 years?
How much money in total will you have after 4 years?

5. Homework
Page 141: Even Numbers
Page 142: 37

6. Discount Problems
Roger paid $126 for a pair of sneakers that were on sale for 30% off. What was the original price?
Rocco bought a computer that was on sale for 25% off. His final cost was $2, What was the original price?
Since the discount is 30%, the discounted price is 70% of the original price.
Since the discount is 25%, the discounted price is 75% of the original price.
The original price of the sneakers was $180
The original price was $2,750.00

7. More Discount Problems
Sammy paid $32.50 for a shirt that was on sale for 35% off. What was the original price?
Sylvester bought a stereo that was on sale for one-third off. His final cost was $ What was the original price?
Since the discount is 35%, the discounted price is 65% of the original price.
Since the discount is 33%, the discounted price is 67% of the original price.
The original price of the shirt was $50
The original price was $585

8. Percent of Change That was easy There’s a formula for that.
A sweater is on sale for $ The original price was $ What is the percent of the mark down to the nearest percent?
A video game is on sale for $10.00 off the original price of $ What is the percent of the mark down to the nearest percent?
The decrease is about 18%
Make sure you use the proper parenthetical formation.
The price of a computer was decreased from $ to $ What is the percent of the mark down to the nearest percent?
The decrease is about 17%
That was easy
The decrease is about 25%

9. Asi de facil More Percent of Change
Use the same formula. Just switch things around a little.
The price of a car goes up from $9, to $11, What is the percent of the increase to the nearest percent?
The population of Pottersville increased from 21,267 to 24,385 over the last 3 years. What is the percent of the increase to the nearest percent?
The increase is about 15%
Make sure you use the proper parenthetical formation.
The price of gas increases from $3.21 to $ What is the percent of the increase to the nearest percent?
The increase is about 15%
Asi de facil
The increase is about 9%

10. Homework
Page 148: 7 – 16 All Questions

11. There’s a formula for that.
Percent of Error
There’s a formula for that.
You estimate that a building is 50 feet tall. The actual height is 57 feet. What is the percent of error in the estimated height rounded to the nearest tenth?
You measure the length of a room to be 21.5 feet. The actual length is feet. Find the percent of error in your measurement rounded to the nearest tenth.
That was easy

12. More Percent of Error Asi de facil
You estimate that a rug is 5 feet by 8 feet. The actual measurement is 4 feet by 8 feet. What is the percent of error in the estimated area of the rug rounded to the nearest tenth?
You estimate that a room is 25 feet by 15 feet. The actual measurement is 26.5 feet by feet. What is the percent of error in the estimated area of the room rounded to the nearest tenth?
Asi de facil

13. Greatest Possible Error
The greatest possible error is one half the measuring unit, for any measurement.
Find the greatest possible error for each measurement.
100 yards
2.8 cm
27.31 inches
12 feet
This was measured to the nearest hundredth of an inch
This was measured to the nearest foot
This was measured to the nearest yard
This was measured to the nearest tenth of a cm
The greatest possible error is
The greatest possible error is
The greatest possible error is
The greatest possible error is

14. Maximum and Minimum Measurements
Use the greatest possible error to find the maximum and minimum measurements of a figure or item.
You measure a room to be 12 feet long.
You weigh a box to be 13.8 pounds.
You weigh a box to be 9.75 kg.
The greatest possible error is 0.5 feet
The greatest possible error is 0.05 pounds
The greatest possible error is kilograms
= 12.5
and
= 11.5
= 13.85
and
= 13.75
= 9.755
and
= 9.745
Maximum Length
12.5 feet
Maximum Weight
13.85 pounds
Maximum Weight
9.775 pounds
Minimum Length
11.5 feet
Minimum Weight
13.75 pounds
Minimum Weight
9.745 pounds

15. Maximum and Minimum Areas
Use the greatest possible error to find the maximum and minimum area of a figure or item.
You measure a room to be 13 ft long and 7 ft wide. Find the maximum and minimum areas.
You measure a wall to be 12 ft wide and 8 ft high. Find the maximum and minimum areas.
The greatest possible error is 0.5 ft
The greatest possible error is 0.5 ft
13 – 0.5 = and = 13.5
12 – 0.5 = and = 12.5
The length could be 12.5 ft to 13.5 ft.
The width could be 11.5 ft to 12.5 ft.
8 – 0.5 = 7.5 and = 8.5
7 – 0.5 = 6.5 and = 7.5
The width could be 6.5 ft to 7.5 ft.
The height could be 7.5 ft to 8.5 ft.

16. Homework
Page : 18 – 22 & 31 – 33
All Questions