Solving Percent Proportion

Solving Percent Proportions (Part 2)

Percent - a ratio out of 100

Proportion - equation stating two ratios are equal

Part - portion of a quantity

Whole - entire amount

How do I make my percent proportion?

• Identify if the given quantity is a PART or a WHOLE amount

• % is always out of 100, so this means " % / 100% "

A helpful tip...

Percentages will have this symbol "%" & always have 100% in the denominator

If a quantity is a PART look for the word "is"

If a quantity is a WHOLE look for the word "of"

Poll

Optometrists estimate that up to 75% of adults wear eyeglasses or contacts. In a lecture hall, 50 college students are wearing either glasses or contacts. About how many students are in the hall?

RESPOND TO THIS: WHAT TYPE OF PROBLEM ARE YOU SOLVING? WHAT'S THE MISSING PIECE OF INFORMATION?

• PART

• WHOLE

• A PERCENT

Multiple Choice

Identify what you are solving for in this situation: 20% of students in class are wearing red. There are 30 students in the class. How many are wearing red?

• Finding the part

• Finding the whole

• Finding a percent

Multiple Choice

Identify what you are solving for in this situation: Five out of 10 cake slices have been eaten. What percent of the cake was eaten?

• Finding the part

• Finding the whole

• Finding the percent

Multiple Choice

Identify what you are solving for in this situation: 300 students have pets that attend school. If 30% of all students have pets, how many students are there in the school?

• finding the part

• finding the whole

• finding the percent

How do you solve for a percent?

• Write out your % Proportion: part/whole = % / 100%

• Scale up or down as necessary

How do I use scaling?

Always write your proportion first: part / whole = % / 100%

Determine what you are solving for: the part, the whole or the %

Next, determine what factor is shared between the numbers you are scaling

Divide and/or multiply as necessary

Multiple Choice

A restaurant has a sign by the door that says "Maximum occupancy: 75 people." What percent of its capacity is 9 people?

• 9%

• 75%

• 12%

• 21%

Multiple Choice

A 20 ounce drink contains 80% fruit juice. How many ounces of fruit juice are in the drink?

• 16 ounces

• 8 ounces

• 14 ounces

• 8.2 ounces

Multiple Choice

60% of toys at a toy store require batteries. If there are 42 toys that require batteries, then how many toys are there altogether?

• 40%

• 70

• 60

• 72