4 1 proportions

Warm Up

• Write in simplest form • Solve.

4

16

48

60

72

44

0.5 15x

Warm Up

• Write in simplest form • Solve.

4 1

16 4

48 4

60 5

72 18

44 11

0.5 15z

0.5 15

0.5 0.5

z

1 30z

Proportions

Some of the most useful items on the math menu

Chapter 4.1

Write 5 to 9

• as a fraction

• as a ratio

• What’s the difference?

5

9

5

9

Are They Equal?

2 5?

10 25

Cross Multiplication• What is 10 x 5?• What is 2 x 25?• If both cross

multiplications statements are equal, the fractions are equal.

Are They Equal?

4 3?

16 12

Cross Multiplication• What is 16 x 3?• What is 4 x 12?

• If both cross multiplications statements are equal, the fractions are equal.

48

48

Are They Equal?

3 48?

4 60

Cross Multiplication• What is 3 x 60?• What is 4 x 48?

48 4

60 5

Find the missing number.

• Using Algebra• 14 x 35 = 10x

10 35

14 x

490 10x490 10

10 10

x

49 1x49 x

Rectangle ABCD ~ WXYZ

• Solve for s.

B

W

D

C

A

X Y

Z

9

27

s

25

left

bottom9

2725

s

Book Sale

• 4 for $1.25• How much is one?

• Label books

and price

Set up a proportion.

Write down labels to help.

4

1.251

Cross Multiply and divide

• 4 for $1.25• How much for one?

4 1

1.25 x

4 1 $1.25x 4 1.25

4 4

x

1 $.325x $.33x

How Tall?

• Man – 6 ft• Man’s shadow – 9 ft• Tree’s shadow – 45 ft

• Set up a proportion.

Proportion

• Man – 6 ft• Man’s shadow – 9 ft• Tree’s shadow – 45 ft

Labels• Actual Height• shadow length

6

45 9

t

9 6 45t

“Lush-Lawn Fertilizer”

• Use 4 lb. for 1500 sq. ft.

• How much to cover 2400 ft2?

Labels:

.lb

area

4

15002400

l

“Lush-Lawn Fertilizer”

4

15002400

l

4 2400 1500x 9200 1500

1500 1500

x

16.3 6 .

3lbs

Assignment

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