Applications with Percents

Applications with PercentsObjective:7.1.01 Develop and use ratios, proportions, and

percents to solve problems

Essential Question: How can I apply my understanding of percents to make more informed shopping decisions?

Vocabulary:Sales Tax: an additional amount of money charged on the

items people buy; the government uses this money to operate the country.

Discount: the amount of money by which the regular price of an item is reduced.

Tip: also known as gratuity, is money given to a person who provides a service, and is added to the cost of that service.

Applications with Percents

Real World Example:Sam has a serious dilemma. He wants to buy PS3 but cannot decide where to buy it from. Target is selling them for $399.99 with a 15% discount. Best Buy is selling them for $375.99 but only a 10% discount. Where should Sam buy his PS3?

Applications with Percents

Best Buy

But What About If…

Applications with Percents

Real World Example:Target was selling them for $399.99 with a 20% discount and Best Buy was selling them for $375.99 and a 15% discount.

Applications with Percents

Best Buy

Applications with PercentsExample 1: Finding Total Cost

A graphing calculator costs $90 and the sales tax is 6%. What is the total cost?

$95.40

Total Cost = Cost of Calculator + Sales Tax

First calculate the sales tax6% OF $900.06 x 90

$5.40

Total Cost $90.00 + $5.40

Total Cost $95.40

Applications with PercentsExample 2: Finding Total Cost

A laptop costs $475 and the sales tax is 7½%. What is the total cost?

$510.63

Total Cost = Cost of Laptop + Sales Tax

First calculate the sales tax

7½% OF $4750.075 x 475

$35.63

Total Cost $475.00 + $35.63

Total Cost $510.63

Applications with PercentsExample 3: Finding Sale Price

A snowboard has a regular price of $169 but is on sale for 35% off. What is the sale price?

$109.85

Total Cost = Cost of Snowboard – Discount

First calculate the discount

35% OF $1690.35 x 169

$59.15

Total Cost $169.00 – $59.15

Total Cost $109.85

Applications with PercentsExample 4: Finding Sale Price

A new coat has a regular price of $185 but is on sale for 33% off. What is the sale price?

$123.95

Total Cost = Cost of Coat – Discount

First calculate the discount

33% OF $1850.33 x 185

$61.05

Total Cost $185.00 – $61.05

Total Cost $123.95

Applications with PercentsExample 5: Finding Total Cost

A meal at Pizza Inn cost $25.85. The tax is 8% and Mr. Williams wanted to leave a 15% tip. What was the cost of the meal?

$123.95

Total Cost = Cost of Meal + Tax + TipFirst calculate

the tax8% OF $25.850.08 x 25.85

$2.07

Next calculate the tip

15% OF $27.920.15 x 27.92

$4.19

When Calculating Tax and Tip:Applications with Percents

Always Remember…Your textbook teaches you to calculate the tax and the tip separately and then add both amounts to the cost of the meal.

However, in a restaurant the tax has already been calculated and added to the cost of the meal.

In my examples, I calculated the tax and added that to the cost of the meal. Next I used the new cost of the meal to determine the tip.

Applications with PercentsExample 6: Finding Percent of Discount

An electric guitar was originally $299.95 but on sale for $179.99. What is the percent of discount?

40%

Discount = Original Cost – Sale Price= $299.95 – 179.99= $119.96

Use the Percent Proportion To

Calculate Percent of Discount

ISOF

%100

Applications with PercentsExample 7: Finding Percent of MarkupIn the last 6 months the average price for a gallon of unleaded gasoline has risen from $2.85 to $3.10. What is the percent of markup?

8.7%

Markup = New Price – Old Price= $3.10 – $2.85= $0.25

Use the Percent Proportion To

Calculate Percent of Discount

ISOF

%100

When Calculating Percents of Markup and Discount:

Applications with Percents

Always Remember…You can use the percent proportion or the percent of change formula to make your calculations.

If you choose to use the percent proportion you have to calculate the change first and use that as your IS and use the original price as your OF.

Independent Practice:Determine the final cost for each example:

1. $99 CD Player, 5% Tax

2. $1,500 Computer, 25% Discount

3. $119.50 Skateboard, 20% Off

4. $4.30 Notebook, 8% Tax

5. $24.95 Book, 4.5% Tax

6. $39.60 Sweater, 40% Discount

Applications with Percents

= $103.95

= $1125.00= $$95.60

= $4.64

= $26.07= $23.76

Summary:Applications with Percents

Always Remember…1) Discounts or Sales are subtracted from the original cost of an item

2) Taxes are added to the cost of an item

3) To determine the Percent of a Discount or Percent of Markup use the percent proportion or percent change formulas

HOMEWORK

Applications with Percents