Simple Problems on Percentages (Primary 5 and Primary 6)

MATHEMATICS

FIRST TERM/FIRST/WEEK/PRIMARY 6

SECOND TERM/WEEK 2/PRIMARY 5

THEME: NUMBER AND NUMERATION

TOPIC: PERCENTAGES

Percentage means quantities divided into hundred parts.

PERFORMANCE OBJECTIVES

By the end of the lesson, the pupils should have attained the following objectives (cognitive, affective and psychomotor) and be able to:

1. recognise the idea (meaning) of percentages;

2. express numbers as a percentage of other numbers;

3. solve problems on percentage increase;

4. solve problems on percentage decrease;

5. find percentages of quantities

ENTRY BEHAVIOR

The pupils are required to already have learned ratio and proportions.

INSTRUCTIONAL MATERIALS

The teacher will teach the lesson with the aid of:

1. Source for correct data on HIV/AIDS.

2. Data chart on HIV/AIDS.

3. Charts with population figures.

METHOD OF TEACHING – Choose a suitable and appropriate methods for the lessons.

Note – Irrespective of choosing methods of teaching, always introduce an activities that will arouse pupil’s interest or lead them to the lessons. 

REFERENCE MATERIALS

Scheme of Work

9 – Years Basic Education Curriculum

New Methods Mathematics Book 6

Champion Mathematics Book 6

All Relevant Material

Online Information

CONTENT OF THE LESSON

LESSON ONE – IDEA OF PERCENTAGE 

Group’s/Pupil’s Activities 1 – Count the number of spaces on the chart 

Total number of spaces is 100.

Group 1 – Count the shaded and unshaped parts 

Shaped parts, _____ and unshaded parts _____. 

Group 2 – Count the shaded and unshaped parts 

Shaped parts, _____ and unshaded parts _____. 

Group 3 – Count the shaded and unshaped parts 

Shaped parts, _____ and unshaded parts _____. 

Teacher’s remark – Percentage means quantities divided into hundred parts. Each of the space presents a percentage. 2 spaces represent 2 percent and it’s written as 2% or 2/100 (as known as fraction) . This symbol (%) represents percentage. 

Pupil’s Activities 2 – Express the shaped and unshaded parts as percentage and fraction. 

Group 1, 

Shaded parts is 35% or 35/100

Unshaded parts is 65% or 65/100

 

The same goes for group 2 and 3.

Pupil’s Exercises/Assignments 

Write these percentages aw fractions.

1. 70%

2. 54%

3. 18%

4. 25%

5. 44%

 

Write these fractions as percentages.

6. 51/100

7. 72/100

8. 42/100

9. 185/100

10. 1725/100

LESSON TWO – EXPRESSING NUMBER OR QUANTITY AS A PERCENTAGE OF ANOTHER 

Teacher’s Activities – Guides pupils to follow the steps below when a number or quantity is to be expressed as a percentage of another.

Teacher’s/Pupil’s Activities 1 – Express 40 as percentage of 80.

= 40/80 x 100

= 1/2 x 100

= 100/2

= 50%

Pupil’s Activities 2 – Express 20 as percentage of 50.

= 20/50 x 100

= 2/5 x 100

= 2 x 20

= 40%

 

Pupil’s Exercises/Assignments 

Express the first quantity as a percentage of the second:

1. 15 to 20

2. 18 months to 24 months.

3. 25 out of 100.

LESSON THREE – PERCENTAGE INCREASE (ADDITION) AND DECREASE (SUBTRACTION) 

• Percentage increase

Teacher’s Activities – Guides pupils to follow the steps below when working on percentage increases or decrease.

Teacher’s/Pupil’s Activities 1 – Increase ₦15 000 by 10%

10% = 10/100

= ₦15 000 x 10/100

= ₦150 x 10

= ₦1500

10% increase is ₦15 000 + ₦1500

= ₦16 000.

 

Teacher’s remark – You add, if it’s percentage increase and subtract, if it’s percent decrease.

Teacher’s/Pupil’s Activities 2 – Decrease ₦15 000 by 20%

20% = 20/10

Therefore,

= ₦15 000 x 20/100

= ₦150 x 20

= ₦3 000

20% decrease is ₦15 000 – ₦3 000

= ₦12 000.

Pupil’s Exercises/Assignments 

1. Increase ₦6 000 by 15%.

2. A new laptop cost ₦50, 000 is decreased by 10%. What is the new price?

Lesson 4 is For Primary 6

LESSON FOUR – WORD PROBLEMS ON PROPORTION 

Teacher’s Activities – Guides pupils to follow the steps below when working on proportion.

Teacher’s/Pupil’s Activities 1

• Mr. Ola buys 50 bags of rice every month. If he plans to increase the quantity by 30%, how many bags will he buy?

30% = 30/10

Therefore,

= 50 x 30/100

= 5 x 3

= 15

30% increase is 50 + 15

= 65 bags.

Teacher’s/Pupil’s Activities 2

• A man bought a carton of milo at ₦5 500, 3 months ago. When she went again to the market to buy another carton, he discovered that the price has decreased by 15%. How much is the present price?

15% = 15/100

Therefore,

= ₦5 500 x 15/100

= ₦55 x 15

= ₦825

15% decrease is ₦5 500 + ₦825

= ₦6 325

 

Pupil’s Exercises/Assignments

1. Transport fare was increased from ₦40 to ₦350, what is the percentage increase.
2. House rent is ₦60 000 per annum. What rent must be charged to give 25% decrease?

PRESENTATION

To deliver the lesson, the teacher adopts the following steps:

1. To introduce the lesson, the teacher revises the previous lesson. Based on this, he/she asks the pupils some questions;

2. Guides pupils to express numbers as a percentage of another;

Pupil’s Activities – Express numbers as a percentage of another.

3. Guides pupils to calculate numbers expressed as a percentage of another;

Pupil’s Activities – Calculate numbers expressed as a percentage of another.

4. Guides pupils to calculate percentage increase and decrease;

5. Guides pupils to solve problems on percentage increase and decrease;

Pupil’s Activities – Solve problems on percentage increase and decrease.

6. Guides pupils to give more examples of everyday activities where percentage increase and decrease is needed;

Pupil’s Activities – Gives examples of everyday activities that require percentage increase.

7. Guides pupils to solve problems in quantitative aptitude on percentage increase or decrease.

Pupil’s Activities – Solves quantitative aptitude on percentage decrease.

CONCLUSION

• To conclude the lesson for the week, the teacher revises the entire lesson and links it to the following week’s lesson.

LESSON EVALUATION

Pupils to:

1. express given numbers as a percentage of another;

2. calculate given numbers expresses as a percentage of another;

3. calculate percentage increase of a given population growth;

4. calculate percentage decrease of a given population growth;

5. solves quantitative aptitude on percentage increase and decrease.