1. 7.1 Ratio and Proportion
Textbook page 357

2. ratio
A comparison of a number a and a nonzero number b using division.
The ratio of a to b can be written as:
a fraction (or an equivalent decimal)
as a:b
or as “a to b” a b

3. simplify the ratio 60 cm to 200 cm
Rewrite as a fraction
Divide the numerator and the denominator by the greatest common factor
Simplify as
60 cm / 20
200 cm / 20
3 cm
10 cm

4. simplify the ratio 3 ft to 18 in
Rewrite as a fraction
Make sure the units are the same, then divide the numerator and the denominator by the greatest common factor
Simplify as
3 ft * 12 in = 36 in
18 in in
36 in / 18
18in / 18
2 in
1 in

5. The perimeter of a rectangle is 84 ft
The perimeter of a rectangle is 84 ft. The ratio of the length to the width is 4:3. Find the length and width of the rectangle.
length : width
4 : 3
P = 2l + 2w
P = 2(4x) + 2(3x)
84 = 8x + 6x
84 = 14x
length
___ ___ 6 6 6 6 6
X = 6
width 6
length = 4(6)
= 24 units 6
width = 3(6)
= 18 units

6. Proportions
An equation that states that two fractions are equal
a = b
c d
b and c are the means
a and d are the extremes
Multiply the means and extremes – the cross products are equal.
Solve the resulting equation
extreme
mean
mean
extreme
bc = ad

7. 5 = y
3( y + 2)
3y =
3y =
y = 8
5(6) =

8. Examples on pg
1) EF = 16, FG = 8
3) x = 4
4) y = 9
5) m = 5

9. Homework
Assignment # 3
Pg 361
Problems 1-46, 56-61