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MATHEMATICS 8UNIT 6

PERCENTSRATIOS / FRACTIONS / DECIMALS

PERCENT OF A NUMBER

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PERCENT

A PERCENT IS A FRACTION WITH ADENOMINATOR OF 100

Any fraction having a denominator of 100 is also anexpression of the percent of the whole being discussed.

In such fractions, the numerator is known as the percent, or %

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What would sixteen twenty-fifths beas a percent?

x 4

x 4

{16 x 4 = 64}

It would be

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RATIOS, FRACTIONS,DECIMALS, AND

PERCENTSFractional numbers can be expressed in several ways:

Fraction Ratio Decimal Percent

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We know the ratio will be

Remember? That line between the numerator

and the denominator is a division line. Thatmeans this fraction is read 23 divided by 37.

Use your calculator for heavens sake!23 divided by 37 = 0.6216216 or 0.62 (rounded)

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0.62 is read 62 one hundredths or

From this, we know the percent is

Look at how the decimalpoint moves when changing adecimal to a fraction. It

moves two to the right.When changing from apercent to a decimal, thedecimal point moves two tothe left.

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PERCENT OF A NUMBERTo find the percent of a number, write the percent as a

decimal and then multiply by the number.

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What % of 44 is 11?Use the two given numbers to create a fraction.

Another way to phrase the question is:What % is 11 out of 44?

Example 2: Something Different

11 divided by 44 = 0.25

0.25 = 25%

Therefore, 11 is 25% of 44

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MATHEMATICS 8UNIT 7

DISCOUNT AND SALE PRICEPST AND GST

COMMISSION AND INTEREST

FINDING THE PERCENT

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DISCOUNT AND SALEPRICE

A discount is a certain percentage of a purchase

price that is taken off an object in an attempt toget consumers to buy the product.

A sale price is the price a consumer pays for a

product after the discount has been subtracted.

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A CD player has a regular price of $598.00. One

day, the same CD player goes on sale with adiscount of 25%. What is the new sale price?

1) Find out how much money the discount

represents:

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PST AND GSTTHESE ARE TWO TAXES FOUND IN MOST

PARTS OF CANADA. THEY WILL EFFECT THEFINAL PRICE YOU PAY FOR PRODUCTS THAT

HAVE THESE TAXES APPLIED TO THEM.

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A mountain bike sells for $550.00. What will be

the final purchase price after taxes?

Note: The final price is the price you pay after

any discounts have been subtracted and after alltaxes have been added.

In this case, the price of the bike + PST + GST

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FINAL PRICE: In Ontario, many items haveboth taxes placed on them. Inthis case, take the price of theitem and multiply by the two

taxes added together or, 15%.

$550 x 0.15 = $82.50

550.00 + 82.50= $632.50

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COMMISSION

COMMISSIONIS A PERCENT OF THE COST OFSOME ITEM SOLD. MANY PEOPLE HAVE JOBS

THAT PAY THEM A COMMISSION

A real estate agent makes 3% of the value of any

home he/she sells.A home selling for $90,000.00 would pay theagent how much?

90,000.00 x 0.03 = 2,700.00

The agent would make $2,700.00 on the sale

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INTEREST

Interestis the amount of money that is charged by a

lender in order for someone else to use their money.Bankspay interestto customers based on theamount of money they have in the bank. Banks

charge interestfor customers borrowing money bytaking out loans.

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When I borrow money from the bank, I have to

pay interest on top of the original amount that Iborrowed. Interest rates can change daily andare often of different amounts.

When I pay the bank back, I owe them the

The amount of theoriginal loan

The amount of money thebank is charging me tolend the money

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Lets say I borrowed $20,000.00 at 8% interest tobuy that splashy little sports model. How muchwill I have paid the bank after retiring the loan?

Principal = 20,000Interest = 20,000 x 0.08 = 1,600

I owe the bank $21,600.00

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Lets say the term of my loan was for 48months. That means that the bank will allow meto make 48 equal payments in order to pay off

my loan. What will my monthly payments be?

This means that I must pay the bank $450 every month in order to keep the car.After 48 months, the car is mine.

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100% OF A NUMBER9% OF A NUMBER IS 72. WHAT IS THE NUMBER?

1) Use the 1% method. To find out what 1% ofthe number is, divide the number known by the

percent.

8 is 1% of the number

were looking for.

To find 100% of thenumber, we multiply what

1% is by 100