Objectives To solve proportions To determine is a ratio can be a proportion

1
ObjectivesTo solve proportionsTo determine is
a ratio can be a proportion
2
(No Transcript)
3
(No Transcript)
4
Proportion-is an equation stating that two ratios
are equal.

• The equation is a proportion because
  they are equal
• If two fractions or ratios do not equal each
  other, then they are not proportions.
• Example If the left side of a proportion
  compares meters to minutes, the right side should
  too.

5
Cross Products of a proportion are always equal

• In the proportion , their cross product
  612 89, which is 72 72. They are equal.
• You can also use the cross product to find if two
  ratios form a proportion. If the left side of the
  equal sign equals the right side, then it is a
  proportion.
• Ratios could also be written as 34 or 3 to 4,
  they both mean

6
Which pair of ratios could form a proportion?

• 1.
• 2.
• 3.

• 4.
• 5.
• 6.

7
Solving Proportions

• You can use cross products to solve a proportion
  that contains a variable.
• Solve
• Write the cross product 15n910
• Multiply 15n90
• Divide each side by 15
• To check your answer you can plug 6 back
  in for n in the original problem. If the
  cross products equal than you found the
  correct answer.
• n 6
  

8
Solve these proportions

• 4.
• 5.
• 6.

• 1.
• 2.
• 3.

9
Think outside the box

• Write two ratios equal to each ratio.
• 250 2. 4 to 12 3. 10025
• A video cassette recorder uses 2 m of tape
  in 3 min when set on extended play.
• The tape is about 240 m long. How many hours
  can you record using extended play?

10

• A map below shows the town of Dover, Butler, and
  Lori. If the actual distance between Dover and
  Butler is 24 miles, how far is it from Dover to
  Lodi?

Lodi
4 in
Butler
Dover
3 in
11

• A blueprint of a house shows that the front is 12
  inches and the house is 14 inches tall. If the
  front of the house is actually 30 feet wide, how
  tall is the house?