ratio and proportion prepared by: josephine libron

Ratio and Proportion

Prepared by: Josephine Libron

Objectives:1. Define ratio and proportion

2. Identify ways in writing ratios

3. Find equal ratios

4. Solve problems involving ratio and proportion using Microsoft Office Word.

5. Make a reflection using PowerPoint Presentation.

Is it good to compare things?

When quantities have different measurements, how can they be

compared?

Ratio- is a comparison of two quantities

Two equal ratios form a PROPORTION.

Ratios and Proportions can be written as a Fraction. We can also use the colon ( : ) in writing ratios and proportions.

Let’s Practice!

Write the ratio or proportion using colon.

1.) 3 cups of sugar for every 5 cups of Flour

2.) 2 men for every 5 cups of rice

3.) 1 book for every 2 pupils

4.) 4/8 = ½

5.) 3/7 = 12/28

Let’s Check!

Click the Button to find the answers.

Answers

1.) 3:5

2.) 2:5

3.) 1:2

4.) 4:8 = 1:2

5.) 3:7 = 12:28

Equal Ratios

To find equal ratios, multiply or divide the given ratio by a fraction equal to 1.

Examples

1. 2

3Solution: Multiply 2 to the given ratio

2

2 x 2 = 4

3 2 6

Therefore, 2 = 4

3 6

2. 8 24

Solution: Divide 8 to the given ratio 8

8 ÷ 8 = 1 24 8 3

Therefore, 8 = 1 24 3

Let’s Practice!

A. Write a ratio equal to each

1.) 1/5

2.) 10/12

3.) 1:2

4.) 2:3

5.) 3:4

Let’s check!

Click the Button to find the answers

1.) 2 4.) 8 : 12 10

2.) 30 5.) 15 : 20 36

3.) 3 : 6

Answers

Let’s Apply

1. Girlie can make five rag dolls from six discarded socks. Write four ratios equal

to this.

Journal #1

Make a journal about the topic and write your learning insights.

Proportion

• A proportion is a statement that two ratios are equal.

• In a proportion, the product of the means is always equal to the product of the extremes

=

To find the missing part of the proportion:

• Multiply the given ratio by a fraction equal to 1 or use the cross product method

• Multiply the means or the extremes. Then divide by the third given number

Examples:

1.) 8 = 32

7 nSolution: Use the cross product method

8n= 224

8n = 224 divide both side by 8

8

n = 28 therefore, 8 = 32

7 28

2.) 3 : 5 = n : 25

Solution: Multiply the means or the extremes

3 : 5 = n : 25

3 x 25 = 75

5 x n = 75

n = 75 ÷ 5

n = 15

Let’s PracticeA.

Find n. Use cross products

1. n = 18 2. 5 = 13

10 4 10 n

B.

Find n.

1. 20 : 24 = n : 6

2. 12 : 28 = n : 42

Let’s check!

Click the Button to find the answers

A.

1. ) 45

2. ) 26

B.

1. ) 5

2. ) 18

Answers

Let’s Apply

1. Empty cans sell at P0.75 for 4. How many does Lina have to sell to earn P11.25?

Solving Problem Involving Ratio and Proportion

Remember:

There are basic steps in solving a problem : Understand, Plan, Carry out the plan and Check.

ProblemFor every 3 metres of bamboo sticks,

three boys can make 5 frames of Christmas lanterns. How many lantern frames can they make with 15 metres of bamboo sticks?

Think

What does the problem ask for?

The number of lantern frames that can be made from 5m of bamboo sticks

What are given? 3m of bamboo sticks

3 boys

5 lantern frames

15m of bamboo sticks

Will I need all the given numbers

The problem is about comparing number of sticks to number of frames. The number of boys is not needed.

PLAN

How will I find the answer?

Compare the number of metres of bamboo to number of frames.

What is the number

sentence? 3 = 15

5 n

Carry Out the Plan

Solve

3 = 15

5 n

5(15) = 75

3n = 75 ÷ 3

n = 25

Give the complete answer

The boys can make 25 lantern frames

Check

Is the answer sensible?

3 metres can make 5 lantern frames. There are five 3s in 15

5 x 5 = 25 (number of lantern frames) The answer is sensible.

Is the computation

correct?

Check

3 x 25 = 75

The computation is correct.

Assignment :

Solve : (Show the basic steps in solving a problem.) 1. Three times a recipe calls for 5 cups of milk. How many cups of milk will be needed for 12 times the recipe?

2. Two out of three booths sell rag dolls. If there are 27 booths, how many of these sell rag dolls?

Activities

1.Make a summary of the whole lesson that has been tackled for the week.

2.Give an example of at least 5 real life problems involving ratio and proportion with the solutions following the basic steps in problem solving. (Write this in the Microsoft Word)

3.Make a reflection based on the lesson for the whole week using PowerPoint presentation.

Finalization of making PowerPoint and the Microsoft Word Activities