Proportions with Two Variables

A ratio is

• comparing a bunch of numbers

• a comparison between 2 quantities

• an estimation of an amount

• a variable

A proportion is a

• ratio statement

• an "if-then" statement

• a statement of 2 ratios

• a comparison

To solve for missing info in a proportion statement you must first

• Cross multiply

• Divide everything

• Get rid of variables

• Guess

Two out of every 3 students in Mr. Pearson’s ninth grade class recycle aluminum cans. If 48 students recycle aluminum cans, HOW MANY STUDENTS are in Mr. Pearson’s class?

Sandra wants to give a party for 60 people. She has a punch recipe that makes 2 gallons of punch and serves 15 people. How many gallons of punch should she make for her party?

A model airplane is made to the scale 1 inch to 24 inches. If the wing of the actual plane is 18 feet long, how long will the model wing be in inches?

If a class has 14 redheads, 8 brunettes, and 6 blondes- What is the REDUCED ratio of redheads to brunettes?

• 4:7

• 14:8

• 8:14

• 7:4

If a class has 14 redheads, 8 brunettes, and 6 blondes- What is the REDUCED ratio of redheads to blondes?

• 3:7

• 14:6

• 6:14

• 7:3

Cindy’s job is to check computer printers for defects. Out of 420 printers she has to check, only 3 of the first 84 have been defective. Using this information, what is the best prediction of the TOTAL NUMBER OF DEFECTIVE PRINTERS?(Set up your ratio)

When determining the expected counts from a two way table, which formula should we use?

• (row total)(column total)/table total

• Number of categories minus 1

• row total minus 1

• column total minus 1