Percentage increase/decrease

• Maatschappijleer
• Middelbare school
• vwo
• Leerjaar 2

Good morning!

Schedule: 

• Learning goals 
• Percentage increase
• Percentage decrease
• Practice
• Homework

Good morning!

Schedule: 

• Learning goals 
• Percentage increase
• Percentage decrease
• Practice
• Homework

Learning goals 

At the end of this lessons I can:

• Calculate percentage increases and decreases
• Calculate the price of something after a discount 
• Calculate a quantity after a percentage increase or decrease

Percentage increase/decrease

Where do you see percentage increase or decrease in your real-life?
Give 1 example

Percentage increase

1. Calculate the percentage of the original value

2. Add this percentage to the original value

Percentage increase

1. Calculate the percentage of the original value

2. Add this percentage to the original value

(3. Write your conclusion)

Ex. Dylan worked 35 hours in November. He has worked 30% more in December. How much did he work in December? 

Dylan worked 35 hours in November. He has worked 30% more in December. How much did he work in December?

Percentage increase

1. Calculate the percentage of the original value

2. Add this percentage to the original value

(3. Write your conclusion)

Ex. Dylan worked 35 hours in November. He has worked 30% more in December. How much did he work in December? 

1. 30% of 35             10% of 35 is 3.5             30% of 35 is 10.5

Percentage increase

1. Calculate the percentage of the original value

2. Add this percentage to the original value

(3. Write your conclusion)

Ex. Dylan worked 35 hours in November. He has worked 30% more in December. How much did he work in December? 

1. 30% of 35             10% of 35 is 3.5             30% of 35 is 10.5

2. 35 + 10.5 = 45.5 hours

Percentage increase

1. Calculate the percentage of the original value

2. Add this percentage to the original value

(3. Write your conclusion)

1. 30% of 35             10% of 35 is 3.5             30% of 35 is 10.5

2. 35 + 10.5 = 45.5 hours

3. He worked 45.5 hours in December

Ex. Dylan worked 35 hours in November. He has worked 30% more in December. How much did he work in December? 

Percentage decrease

1. Calculate the percentage of the original value

2. Subtract this percentage from the original value

(3. Write your conclusion)

There is a pair of trainers in the sale. They were originally €60.

 They have 20% off. How much do I pay for them?

There is a pair of trainers in the sale. They were originally €60.
They have 20% off. How much do I pay for them?

Percentage decrease

1. Calculate the percentage of the original value

2. Subtract this percentage from the original value

(3. Write your conclusion)

1. 20% of 60                        0.20 ⋅ 60 = 12.0                so 20% of 60 is 12

There is a pair of trainers in the sale. They were originally €60.

 They have 20% off. How much do I pay for them?

Percentage decrease

1. Calculate the percentage of the original value

2. Subtract this percentage from the original value

(3. Write your conclusion)

1. 20% of 60                        0.20 ⋅ 60 = 12.0                so 20% of 60 is 12

2. 60 - 12 = 48

There is a pair of trainers in the sale. They were originally €60.

 They have 20% off. How much do I pay for them?

Percentage decrease

1. Calculate the percentage of the original value

2. Subtract this percentage from the original value

(3. Write your conclusion)

1. 20% of 60                        0.20 ⋅ 60 = 12.0                so 20% of 60 is 12

2. 60 - 12 = 48

3. With the discount I pay €48 for the trainers.

There is a pair of trainers in the sale. They were originally €60.

 They have 20% off. How much do I pay for them?

Practice

1. Increase €300 by 10%

2. Increase $80 by 75%

3. Decrease RP 220 by 15%

1. Increase £96 by 15%

2. Increase € 256 by 5%

3. Decrease € 72 by 20%

4. Decrease € 321 by 2%

Level 1                                                 Level 2

Practice

1. €330

2. $140

3. RP 187

1. £110.40

2. € 268.80

3. € 57.60

4. € 314.58

Level 1                                                 Level 2

Holiday

Louise needs some help to book her Winter holiday.

There are four possible destinations to choose from, but Louise wants to find the cheapest deal.

She wants to go away for 2 weeks. The holiday is for 2 adults and 2 children.

In pairs work out the cost of each holiday and decide which is the best value.

Which destination should Louise choose?

1. Thailand
2. New York
3. Hawaii
4. Australia

Holiday 

Thailand - €2522.52

New York - €2563.60

Hawaii - €2541.90

Australia - €2521.26

In class work

p. 189 : 9F               1, 3, 5, 7, 8abc

p. 190-191 : 9G             1, 3, 6

                                  

Homework

Create your own percentage problem.

- the more complex your context and problem is, the better

- provide the correct answer + working out for your problem as well

- I will choose problems for tomorrows lesson