1. Ratio – comparing same things
2 apples to 4 apples
2 apples / 4 apples
2 apples : 4 apples
Rate – comparing different things
2 apples to 4 basketballs
2 apples / 4 basketballs
2 apples : 4 basketballs

2. Unit Rate – comparing different things – (the denominator is always one)
2 apples to 1 cat
2 apples / 1 cat
2 apples : 1 cat
Unit Cost or Price – comparing different things – (the denominator is always one & the money always comes first)
$2 to 1 ounce
$2 / 1 ounce
$2 : 1 ounce

3. Example 1: Determine whether the following ratios form a proportion.
a.) b.)
Yes, because cross products are equal 60 = 60
No, because cross products are not equal 10 = 8

4. Example 2: Solve each proportion below by using the cross products.
a.) b.)
c.) d.)
Algebra Method:
2x = 90 Divide by 2 on both sides
x = 45
Algebra Method:
12x = 84 Divide by 12 on both sides
x = 7
Baby Math Method:
(9*10)/2
Baby Math Method:
(4*21)/12
Algebra Method:
15x = 180 Divide by 15 on both sides
x = 12
Algebra Method:
8x = 72 Divide by 8 on both sides
x = 9
Baby Math Method:
(12*6)/8
Baby Math Method:
(20*9)/15

5. Example 3: Set up a proportion for each scenario below and solve by doing the cross products.
a.) Andy paid $1.29 for 3 pieces of candy. At that rate, what would 8 pieces of candy cost?
b.) You are visiting friends in Estonia. Suppose the exchange rate is kroons = 1 dollar. How many Estonia kroons will you receive if you have $500?
x = $3.44
Dollars
Candy
Kroons
Dollar
x = $6340