3.6 Ratios and Proportions
Ratio: a comparison of two numbers by division
Proportion: an equation stating that two ratios are equal
1. Determine whether the ratios
4
24
and
form a proportion.
5
30
2. Use cross products to determine whether each pair of ratios forms a proportion.
a.
0.4 0.7
,
0.8 1.4
b.
6 24
,
8 28
Means-Extremes Property of Proportion:
In a proportion, the product of the extremes is equal to the product of the means.
a c
 In 
, a and d are the extremes and c and b are the means.
b d
a c
 If  , then ad = bc.
b d
3. Solve the proportion
n 24

.
15 16
4. Solve the proportion
4 2
 .
x 10
5. Trent goes on a 30-mile bike ride every Saturday. He rides the distance in 4
hours. At this rate, how far can he ride in 6 hours?
6. The scale of a map for Crater Lake National Park is 2 inches = 9 miles. The
distance between Discover Point Na Phantom Ship Overlook on the map is about
3
1 inches. What is the distance between these two places?
4