9-1: Relating Fractions,

Decimals, and Percents

IWBAT convert a percent to a fraction or decimal and convert a fraction or

decimal to a percent.

Percent – A special ratio that compares a

number with 100 Percent means “per hundred”

Vocabulary

Fraction to Decimal and Percent

Fraction to Decimal

Divide the numerator by the denominator

Put the whole number in front of decimal, if needed

Fraction to Percent

Convert the fraction to a decimal

Move the decimal to the right twice

Add the % sign

Examples

1) 2) 3)

Percent to Decimal and Fraction

Percent to Decimal

Remove the % sign Move the decimal

left twice

Percent to Fraction

Remove % sign Put number over 100 Simplify

Examples

1) 15% 2) 2.75 3) 120%

Decimal to Fraction and Percent

Decimal to Fraction

Look at the place value of the fraction

Place decimal over corresponding place value

Simplify Put whole number in

front if there is one

Decimal to Percent

Move decimal right twice

Add the % sign

Examples

1) 3.15 2) 0.095 3) 0.65

9-2: Estimating Percent

IWBAT estimate percents of numbers between 0% and 100% using multiples

of 10% or fractions

Round the percent to the nearest 10% Round the number to the nearest 10s

If the number is less than 10, do not round it Change the percent to a decimal Multiply

Estimating Using Rounding

Examples

1) Estimate 28% of 71

2) Estimate 9% of $19.99

3) Estimate 82% of 202 4) Estimate 89% of 6

Memorize the following common percent to

fraction conversions:

Round the whole number to the nearest 10s Choose the corresponding fraction Multiply

Estimating Using Fractions

10% 20% 25% 33% or

34%

50% 66% or

67%

75% 90%

Examples

1) 75% of 200 2) 39% of 600 3) 21% of 400

4) 26% of 19 5) 92% of 48

9-3: Finding a Percent of a

Number

IWBAT use a proportion to set up percent problems and solve using cross

products.

Think of problems as asking, “What is . . . ?”

Percent Proportion Formula

9-4: Is an Estimate Enough?

IWBAT determine whether an estimate is a sufficient solution or whether an

exact amount is needed.

9-5: Mental Math: Finding a Percent

of a Number

IWBAT use mental math to calculate percents of numbers

Use the same rules as estimating percent

9-6: Solving Percent Problems Using Equations

IWBAT write and solve percent equations.

Break up the problem and substitute into

proper place in proportion formula

Use the Percent Proportion Formula

Write a proportion and solve.

What number is 25% of 62?

1) Break into sections. What number is25%Of 62

2) Substitute into formula

25100

=𝑛62

3) Simplify, if possible

4) Cross-Multiply

Examples

1) 15 is what percent of 75?

2) What number is 40% of 88?

3) What percent of 90 is 27?

4) What is 120% of 360?

5) 16 is what percent of 40?

6) The 6th grade class is having a book sale. Their order included 300 novels. So far, 180 novels have been sold. What percent of the novels have been sold?

9-7: Write an Equation

IWBAT writ and solve one-step linear equation involving percent

9-8: Finding Sales Tax

IWBAT find sales tax and total cost.

Tip – A percentage of the total of your bill that

you give for a service Tax – A percentage of the total of your bill that

you pay to the government

Vocabulary

Finding Sales Tax and Total Cost

You buy a soccer ball priced at $14.69. If the rate of the sales tax is 6.5%, what is

the total cost of the ball?

1) Convert the percent to a decimal

6.5% = 0.065

2) Multiply the decimal by the price. This is the sales tax.

14.69 0.065

0.95485

3) Round UP to the nearest cent

0.95485 0.96

4) Add to the price to find the total cost

$14.69 + 0.96

$15.65

Examples

Find the sales tax and the total cost. Round the sales tax up to the nearest cent.

1) Cost: $19 Rate of sales tax: 8%

2) Cost: $412 Rate of sales tax: 6%

3) Cost: $62.50 Rate of sales tax: 5.5%

4) A basketball costs $30. The rate of sales tax was 5%. Find the total cost of the basketball.

9-9: Computing Discount

IWBAT find discount and sales price.

Finding the Discount and the Sale Price

The Nature Shop had a 25% sale on kaleidoscopes. Michael bought one originally priced at $15.99. How much did he pay

on sale?

1) Convert the percent to a decimal

25% = 0.25

2) Multiply the decimal by the original cost. This is the discount.

15.99 0.25

3.9975

3) Round the discount DOWN to the nearest cent.

3.9975 3.99

4) Subtract the discount from the original price to find the sale price.

$15.99 – 3.99

$12.00

Examples

1) Regular price: $200 Rate of discount: 10%

2) Regular price: $56 Rate of discount: 25%

3) Regular price: $66 Rate of discount: 33

4) Tommy bought two kaleidoscopes on sale for 20% off. If each kaleidoscope cost $29 before the sale, what did Tommy pay for both on sale?

9-10: Using the Interest Formula

IWBAT use the simple interest formula to calculate interest and find the total

amount earned or charged.

Interest – the amount of money paid for the use

of money Investments, loans, savings

Interest Formula: I = prt I is interest p is principal (original amount deposited or

borrowed) r is the rate of interest (the percent earned or

charged) t is the time the money is in the account or is

borrowed (measured in years)

Vocabulary

Find the interest and total with interest

You put $200 in a savings account earning 5.5% simple interest per year. What is the total you will have in your account after one year?

2) Rewrite the interest formula

I = prt

1) Identify each variable I = ?p = $200r = 5.5% = 0.055t = 1

3) Substitute. Solve the equation to find interest.

I = prtI = 200(0.055)(1)I = $11

4) Add the interest to the principal

$200 + 11 = $211

Examples

1) Principal: $6,000 Rate: 5% Time: 5 months

Find the interest and the total with interest.

2) Principal: $4,500 Rate: 18% Time: 6 months

3) Principal: $500 Rate: 7.5% Time: 1 year

4) You want to borrow $500,000 for 6 months at 12% interest. How much money will you owe the bank?