Percents as Fractions and Decimals

What is a Percent?

• Percent is a special ratio compared to 100

• Fractions, Decimals and Percents can all be equal ways of saying the same value.

• Today we will practice changing from percents to fractions to decimals.

Percent to Fraction

Percent as a Decimal

Fraction as a Percent

• Remember a percent has a denominator of 100.

• Make an equivalent fraction by multiplying or dividing and so the denominator is 100.

Fraction to a Percent Method 2

• Fractions can also be division problems

• So divide numerator by denominator

• Look at the digits up to the hundredths place to find the percent

Percent Change

describes how much a quantity decreases or increases in relation to the original amount

for example: the percent off in this sale is the percent change

Calculating Percent Change

Example 1

The enrollment at a middle school increased from 650 students to 780 students in 5 years. What is the percent increase in the number of students enrolled at the school?

Example 1

Example 2

Sales Tax

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Moving onto Tips/Gratuity

• Tips or Gratuity is a small amount of money in return for a service.

• The total price is the regular price of the service PLUS the tip!

• Fun Fact: It is common to tip your servers 20%... just saying! :)

Example #2 - Tips

• A customer wants to tip 15% on a restaurant bill that is $35. What will be the total bill with the tip?

• Step 1: Find the amount to tip! We do this by taking the decimal from of the % and multiplying it by the bill amount.

• $35 * 0.15 = $5.25

• Step 2: Add the tip to the total of the bill!

• $35 + $5.25 = $40.25

• So the total bill is $40.25

Discount & Markup

Pre-Algebra

Example #3 - Markup!

• A markup is a percent INCREASE on an item!

• A store buys a phone for $600 and wants to sell it with a markup of 35%. What is the selling price of the phone?

• Step 1: Find the amount of markup (take the money amount and multiply it by the decimal of the percentage)

• $600 * 0.35 = $210

• Step 2: ADD the amount of markup to the original price.

• $600 + $210 = $810 selling price!

Discount

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

Original cost -discount = Sale Price

Lesson 2.6   Commission and fees

Simple Interest

The "r" stands for rate and is going to be given to you in a percentage.

If your "t" isn't given to you in years, convert it.

• days = divide by 365 (leap years don't really count in finance)

• weeks = divide by 52

• months = divide by 12

Remember, we are talking about money, so you need dollars and cents.

Round to the nearest hundredth. No half pennies until we talk about investing (or debt) [Stay away from debt!!!!!].

Percent Error

Unit 4