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4.03 Discounts, fees and markups

Introduction

We have already learned about  percent increase and percent decrease.  . We will now apply these concepts to real life situations like calculating discounts, markups and markdowns, and fees.

Discounts and markdowns

Everyone will have seen stores advertising, "25\% off", or "pay less when you pay cash." These are both examples of discounts. A discount is a reduction in price, or a percent decrease. Businesses often use discount sales to encourage people to buy from them so it's important to be able to calculate discounts to make sure you're getting a great deal.

Another example of a percent decrease is a markdown, which is an amount by which we lower the selling price. Markdown is seen when businesses give out coupons, and have special sales events to encouage more customers to purchase.

Let's look at the following example on how we apply percent decrease to calculate a discount.

Examples

Example 1

Steph is going to buy a hat that is marked at 75\% off. The original price is \$36.

a

What is the value of the discount in dollars?

Worked Solution
Create a strategy

To find the discount amount, multiply the original price by the percent discount. Remember that percent means 'divided by 100'.

Apply the idea
\displaystyle \text{Discount}\displaystyle =\displaystyle 36\times \dfrac{75}{100}Multiply the original price by the percentage discount in fraction form
\displaystyle =\displaystyle \dfrac{2700}{100}Evaluate the multiplication
\displaystyle =\displaystyle 27Evaluate the division

The discount is \$27.

b

What is the price that Emily will pay for the dress?

Worked Solution
Create a strategy

To find the discounted price, subtract the discount from the original price.

Apply the idea
\displaystyle \text{Discounted price}\displaystyle =\displaystyle \$36-\$27Subtract the discount from the original price
\displaystyle =\displaystyle \$9Evaluate.

The discounted price is \$9.

Reflect and check

We have decreased the amount by 75\%, which means that Emily is paying the remaining 25\%, or 100\%-\text{percent decrease} .

We could have calculated the discounted price by:

\displaystyle \text{Discounted price}\displaystyle =\displaystyle 36\times \dfrac{25}{100}Rewrite 25\% as a fraction and multiply by the original price
\displaystyle =\displaystyle \dfrac{900}{100}Evaluate the multiplication.
\displaystyle =\displaystyle 9Evaluate the division.

We get the same answer. The discounted price is \$9.

Idea summary

Discounts and markdowns are examples of percent decreases. We subtract the amount of discount or markdown from the original price to find the sale price. We can also multiply the original price by 100\%-\text{percent decrease} to get the sale price.

Fees and markups

On the other hand, we can have a percent increase like a markup. This is when the price is increased to cover the cost. For example, if we buy a cellphone for \$200, we may sell it with 5\% markup to earn a profit.

We may also apply percent increase in additional fees, which is a charge or payment for professional services. For example, a service fee for hotel services or a fee to use a credit card.

Markdowns and discounts involve lowering the costs for consumers, to increase the quantity that people may purchase. Markups and fees imply an increase in the cost, increasing the profit for the supplier.

Examples

Example 2

A brush set which costs \$75 is marked up by 20\%. What is the markup amount for the brush set?

Worked Solution
Create a strategy

Remember that markup involves percent increase. Increasing by 20\% is the same as multiplying 100\%+20\% or 120\%.

Apply the idea
\displaystyle \text{Markup}\displaystyle =\displaystyle \$75\times \dfrac{120}{100} Convert 120\% to a fraction and multiply to the original price
\displaystyle =\displaystyle \dfrac{9000}{100} Evaluate the multiplication
\displaystyle =\displaystyle 90Evaluate the division.

The markup amount is \$90.

Example 3

A contractor was hired to build a house which will cost \$300\,000. The contractor also includes a service fee of \$45\,000 for the overall cost of the contract.

What percent of the cost of the house is the contractor's percentage fee?

Worked Solution
Create a strategy

Find the percentage rate as a ratio of the percentage fee and the cost of the house.

Apply the idea
\displaystyle \dfrac{45\,000}{300\,000}\displaystyle =\displaystyle \dfrac{x}{100}Set up a proportion to find the percent.
\displaystyle =\displaystyle \dfrac{45\,000}{300\,000}\div \dfrac{3000}{3000}Divide the numerator and denominator by 3000 to find an equivalent fraction with a denominator of 100
\displaystyle =\displaystyle \dfrac{15}{100}Evaluate the division
\displaystyle =\displaystyle 15\%Convert fraction to percent

The contractor charges a percent fee of 15\%.

Idea summary

Fees and markups are examples of percent increases. We add the fee or the markup to the original price to find the full price. We can also multiply the original cost by 100\% + \text{percent increase} to find the full price.

Outcomes

7.RP.A.3

Use proportional relationships to solve multistep ratio and percent problems.

7.EE.B.3

Solve multi-step real-life and mathematical problems posed with positive and negative rational numbers in any form (whole numbers, fractions, and decimals), using tools strategically. Apply properties of operations to calculate with numbers in any form; convert between forms as appropriate; and assess the reasonableness of answers using mental computation and estimation strategies.

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