LESSON 59: �FINDS THE PERCENTAGE IN A GIVEN PROBLEM

Prepared by:

Ruze Mi

Saavedra Saway Central Elementary School

DRILL �(MENTAL COMPUTATION ON CHANGING PERCENT TO RATIO, DECIMAL TO PERCENT, FRACTION TO PERCENT AND VICE VERSA)

Mechanics:

a. Have two lines of pupils of the same number of members if possible.

b. Each pupil in front of the line renames the ratio to percent, decimal to percent,

fraction to percent and vice versa by writing the number on the board as

the teacher flashes the card.

c. As soon as the pupil writing his answer on their sheet finishes, he has to touch

the second pupil in the line and goes at the end of the line.

e. The teacher flashes the next card and repeat steps in letter b and c.

f. The teacher checks the answers and adds the scores after the last card is

flashed.

REVIEW �(IDENTIFYING THE BASE, PERCENTAGE AND RATE IN A PROBLEM)

Mechanics:

a. Divide the class into 4 groups. One representative from each group stands at the back of the classroom.

b. Flash the strips of cartolina with a short problem written on it. The

representative from each group will identify the missing/unknown

part in the problem.

c. The first one who gives the correct answer will get the point.

d. The game continues until all the pupils from each group have participated.

e. The group with the most number of points wins.

� � WHAT’S YOUR TARGET SCORE IN A 20-ITEM TEST? WHAT PASSING GRADE IS IT? (75%, 80%, 90% OR 100%? THE PUPILS HAVE THE FREEDOM TO CHOOSE.

Motivation

Ask: Do you study your lesson every day? Do you listen well and participate in class discussion?

Ask: Why do you need to study? Will it help you prepare for your future?

Presentation

Vincent, a boy from a fishing village is a diligent and studious pupil. He goes to school and every day and does his work well. He never skips studying his lesson every night. When he took their 50-item quarter examination he got 96% of it correctly? What is his score? 

Ask:

• Who is the boy from the fishing village?
• How is he as a pupil?
• Did he do well in school? How do you know?
• How many items is their test?
• What rating does Vincent get in the test? Is this a high rating? How do you know?
• Will you do the same? Why?

Ask the pupils to work in groups in solving the problem.

Step 1:

Arranged the numbers vertically.

50

x 96

Step 2:

Move the decimal point of 96% twice from right to left.

50

x 0.96

Step 3:

Multiply the numbers following the steps in multiplication.

50

x 0.96

300

450

+ 000__

048.00

48 – number of correct items Vincent got out of 50-item test.

After the group presented and checked their work, call on the leader to relate what they have done to solve the problem.

Ask:

• How do we solve for the percentage?
• Did you move the decimal point of the rate from right to left?
• How many move of decimal point do we move?

In the recent election held at Brgy. Masikap, it showed that the winning Brgy. Captain received 78% of the total votes from 160, 000 population of the barangay. How many people voted the winning Brgy. Captain?

How will you solve for the answer for the problem?

Here are the steps in analyzing and solving word problems.

Step 1: Identify the rate and the base in

the given problem.

• Rate- 78%

• Base – 160, 000

• Percentage - ?

Step 2: Transform the problem in equation form.

• 160, 000 x 78% = n

Step 3: Use the formula in finding the percentage.

Change the rate to a decimal then multiply the base.

• P = B x R

= 160, 000 x 0.78

Step 3: Solve. Follow the steps use in multiplication. Put the decimal point on its corresponding place.

160 000

x 0.78

1 280 000

+ 11 200 00_

12 480 0.00

124, 800 – number of people who voted the winning Brgy. Captain

Complete the table by finding the percentage.

A. Change percent to fraction then solve.

1. 4% of 25 = ___ 6. 10% of 20 = ____

2. 5% of 80 = ___ 7. 25% of 40 = ____

3. 5% of 90 = ___ 8.120% of 50 = ____

4. 9% of 81 = ____ 9.40% of 1206 = ____

5. 6% of 12 = ____ 10. 20% of 80 = ____

B. Change percent to decimal then solve.

1. 75% of 64 = ____ 6. 37.5% of 90 = ____

2. 16% of 80 = ____ 7. 12.8% of 60 = ____

3. 14% of 56 = ____ 8. 43.2% of 150 = ____

4. 60% of 30 = ____ 9. 67.5% of 120 = ____

5. 50% of 18 = ____ 10. 24.8% of 100 = ____

Summarizing the Lesson

In finding the percentage of a given number follow these steps:

• Find the rate in the given problem.
• Arrange the numbers in vertically.
• Move the decimal point of the given rate twice from right to left.
• Multiply the numbers following the steps in multiplication.
• Count the number at the right of the decimal point which will decide where to put the corresponding decimal point.

Another way of solving percentage is by changing percent to fraction. You will be guided by following these steps:

1. Convert percent to fraction. You can use the lowest term of the fraction if you want.

2. Multiply the given number to the numerator. If possible use cancellation.

3. Divide the product of the given number and the numerator by the denominator.

Solve each problem.

1. There are 40 students in a class. If 95% of them were present, how many students attended their class?

2. Among the 1 400 students who attend school, 12% are left-handed. How many are left-handed? How many are right-handed?

3. Jenny answered 95% of her test correctly. If there were 60 items in the test, how many items did she answer correctly? How many mistakes did she make?

4. In a Math competition, 30 boys and 20 girls joined. At the awarding ceremony, 20% of

the boys and 15% of the girls were awarded prizes. How many received prizes?

7. A talk show hosts has done 3 225 shows, 20% of which were shot on tape (not live). How many of the shows were taped? How many were live?

8. The country’s biggest coliseum sold 20 million tickets for different events during one year. Of these tickets 77.5 % were for sporting events. How many tickets were sold for sporting events?

9. During the basketball season, George shot 175 free throws. He made 88% of them. How many free throws did George make?

10. 120 points are given to each of two tests. If a boy gets 63 points in one test, how many points must he get in the second test to get 60% for both tests?

Assessment

Complete the table by identifying the percentage of the following items.

Solve the following percentage problems.

1) Forty-six percent of people surveyed said that they exercised on a fairly regular basis. If 12 100 people were surveyed, how many of them exercise?

2) The price of gasoline decreased by 18%. If a liter of gasoline sold P 21.15 before the decrease, what was the amount of the decrease?

3) In a certain city, about 25% of the people are between the ages of 20 and 40 years. If the city

population is 1 430 000, how many people are between those ages?

4) The Jimenez family planned to save at least 7.5% of their monthly income of P 12 500. How

much did they plan to save?

5) Marvin, a basketball player, usually scores 80% of his field shots. If he attempted 40 field

shots during a game, how many did he score ?

Home Activity

Answer the following.

1. What is 25% of 4?

2. N is 50% of 2.

3. 200 % of 3 is what number?

4. 75% of 12 is ____?

5. 60% of 30 is N.

6. 30% of 600 is what number?

7. 230% of 90 is N.

8. 150% of P 400 is _____.

9. 36% of 95 is N.

10. 48% of 290 is what number?