Real Life Applications of Proportions

Real Life Applications of Proportions

Proportions can be used to solve problems involving percents.

•  $\frac{part}{whole}=\frac{percent}{100}$  

Sales Tax and Gratuities

Percents are often used when describing and solving problems involving sales tax and gratuities. The sales tax rate varies by state, and sometimes, by city. It is a percent of the total cost of items purchased.

Lets work on some examples together

Juan bought a laptop for $650 and a power adapter for $59. If the sales tax rate is 6%, what was the total tax that Juan paid? What was Juan's total?

• Step 1. What is the question asking?

Multiple Select

We need to find the tax and the total amount paid?

• True

• False

Juan bought a laptop for $650 and a power adapter for $59. If the sales tax rate is 6%, what was the total tax that Juan paid? What was Juan's total?

• Step 1. What is the question asking?

•  What is the amount we are calculating tax on? 

  You get this by adding the cost of the laptop and the power adapter.

  
  

Multiple Choice

What is the total amount we need to calculate tax on?

• $709

• $790

Juan bought a laptop for $650 and a power adapter for $59. If the sales tax rate is 6%, what was the total tax that Juan paid? What was Juan's total?

• Step 1. What is the question asking?

• Step 2. What is the amount we are calculating tax on? 

  You get this by adding the cost of the laptop and the power adapter.

• Step 3. Now use cross multiplication to find the TAX.

  How much is the tax?

  
  

Multiple Select

How much is the tax on both items?

• $4254

• $42.54

• $24.52

• $54.24

Juan bought a laptop for $650 and a power adapter for $59. If the sales tax rate is 6%, what was the total tax that Juan paid? What was Juan's total?

• Step 1. What is the question asking?

• Step 2. What is the amount we are calculating tax on? 

  You get this by adding the cost of the laptop and the power adapter.

• Step 3. Now use cross multiplication to find the TAX.

  How much is the tax?

• Add the tax to the total of the laptop and the power adapter for the answer to the second part of the question...

  What was Juan's total?

  
  

Multiple Select

What was Juan's total?

• $751.54

• $771.54

Let's look at another question

Patricia took her family out to breakfast. The total cost of the food was $24. She left a 15% tip for the waiter. How much did Patricia leave for a tip?

What are we trying to find in this question?

Multiple Select

What is the question asking?

• How much the tip would be.

• The amount of the bill with the tip included.

So let's use cross multiplication to find the amount of the tip.

 $\frac{n}{24}=\frac{15}{100}$  

 $100n\ =\ 360$  

 $\frac{100n}{100}=\frac{360}{100}$  

 $n\ \ =$ 

Multiple Select

n =

• $3.60

• $360

Multiple Choice

Your parents took your family out to dinner. Your parents wanted to give the waiter a 15% tip. If the total amount of the dinner was $42.00, what should be paid to the waiter as a tip?

• $6.30

• $8.40

Multiple Choice

John and his family went out to eat at their favorite restaurant. The bill for the food was $65.00, and they a left 20% tip for the server. What was the total cost of their meal (including tip)?

• $88.00

• $68.00

• $78.00

Multiple Choice

A $250 Suede Jacket is on sale for 20% off. How much should you pay for the jacket?

• $195

• $175

• $250

• $200

Multiple Choice

A bracelet that regularly sells for $44 is on sale for 25% off. Find the sale price of the bracelet.

• $33

• $34

• $35