Volume%20of%20Prisms

1
Calculating Percentages
Int 2
Simple Interest / Compound
Compound Interest
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Appreciation / Depreciation
Inflation / Working back
2
Starter
Int 2
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3
Calculating Percentages
Int 2
Compound Interest
Appreciation More
Simple Interest
Just Calculating Percentages
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Depreciation Less
Inflation Rising Prices
Working backwards
4
Calculating Percentages
Int 2
Learning Intention
Success Criteria

1. To know the meaning of the term simple interest.

• To understand the
• term simple interest and compound interest.

1. To know the meaning of the term compound interest.

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3. Know the difference between simple and
compound interest.
5
Calculating Percentages
Just working out percentages
Int 2
Simple Interest
I have 400 in the Bank. At the end of each year
I receive 7 of 400 in interest. How much
interest do I receive after 3 years. How much do
I now have?
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6
Calculating Percentages
Int 2
Now try Exercise 1 Ch2 (page 8) Odd Numbers
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7
Calculating Percentages
Interest calculated on new value every year
Int 2
Compound Interest
Real life Interest is not a fixed quantity year
after year. One years interest becomes part of
the next years amount. Each years interest is
calculated on the amount at the start of the year.
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Principal value
8
Calculating Percentages
Interest calculated on new value every year
Compound Interest
Int 2
Daniel has 400 in the bank. He leaves it in the
bank for 3 years. The interest is 7 each year.
Calculate the compound interest and the amount he
has in the bank after 3 years.
Y1 Interest 7 of 400 28
Simple Interest
Amount 400 28 428
Interest 7 of 400 28
Y 2 Interest 7 of 428 29.96
3 x 28 84
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Amount 428 29.96 457.96
Y 3 Interest 7 of 457.96 32.06
Amount 457.96 32.06 490.02
Compound is 490.02 - 400 90.02
Simple Interest is only 84
9
Calculating Percentages
Int 2
Now try Exercise 2 Ch2 (page 8 9)
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10
Starter
Int 2
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11
Calculating Percentages
Int 2
Learning Intention
Success Criteria

1. To calculate compound interest using calculator..

1. To understand how to use the calculator to
   calculate compound interest easier.

• Show appropriate working
• when solving problems.

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12
Calculating Percentages
Int 2
This is called the multiplier.
Using a calculator to do Compound Formula
n period of time Days, months years
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I initial value
IMPORTANT Can only use this when percentage is
fixed
increase or decrease
V Value
13
Calculating Percentages
Int 2
Using a calculator to do Compound questions
Calculate the money in the bank after 3 years if
the compound interest rate is 7 and the initial
value is 400.
n 3
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I 400
increase 10.071.07
V 400 x (1.07)3 490.02
14
Calculating Percentages
Int 2
Using calculator to calculate Compound questions
In a jar bacteria grows 4 every hour. Initially
there were 200 bacteria in the jar. How many
bacteria are in the jar 4 hours later.
n 4
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I 200
increase 10.041.04
V 200 x (1.04)4 234
15
Calculating Percentages
Int 2
Using calculator to calculate Compound questions
A car reduces in price by 14 each year.
Initially it cost 12 500. much is it worth 5
years later.
n 5
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I 12 500
increase 1-0.140.86
V 12 500 x (0.86)5 5880.34
16
Calculating Percentages
Int 2
Now try worksheet
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17
Starter
Int 2
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18
Calculating Percentages
Int 2
Learning Intention
Success Criteria

1. To know the terms appreciation and depreciation.

1. To understand the terms appreciation and
   depreciation.

• Show appropriate working
• when solving problems containing appreciation
  and depreciation.

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19
Calculating Percentages
Int 2
Appreciation / Depreciation
Appreciation Going up in value e.g. House value
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Depreciation Going down in value e.g. car value

20
Quicker Method Easier 1.79 x 64995 116341.05

• Average house price in Ayr has appreciated by
  79 over past 10 years.
• If you bought the house for 64995 in 1994 how
  much would the house be worth now ?
• Appreciation 79 x 64995
• 0.79 x 64995
• 51346.05
• New value Old Value Appreciation
• 64995 51346.05
• 116341.05

Just working out percentages
21
Calculating Percentages
Int 2

• A Mini Cooper cost 14 625 in 2002
• At the end 2003 it depreciated by 23
• At the end 2004 it will depreciate by a further
  16
• What will the mini cooper worth at end 2004?
• End 2003
• Depreciation 23 x 14625
• 0.23 x 14625
• 3363.75
• New value Old value - Depreciation
• 14625 - 3363.75
• 11261.25

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22
Calculating Percentages
Int 2

• End 2003
• Depreciation 23 x 14625
• 0.23 x 14625
• 3363.75
• New value Old value - Depreciation
• 14625 - 3363.75
• 11261.25
• End 2004
• Depreciation 16 x 11261.25
• 0.16 x 11261.25
• 1801.80
• New Value 11261.25 - 1801.80
• 9459.45

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23
Calculating Percentages
Int 2
Now try MIA Ex 4 Ch2 (page 12) Odd Numbers
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24
Starter
Int 2
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5cm
6cm
25
Calculating Percentages
Int 2
Learning Intention
Success Criteria

1. Know the term inflation.

• Understand term inflation
• and work out associated real-life problems.

1. Work out real-life problems involving inflation.

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26
Calculating Percentages
Measure of how much prices rise each year.
Int 2
Inflation
Inflation is normally given in percentage form
and is normally in the range 0 10
Example 1
In 2004 a worker received a wage of 300 per
week. If inflation is 2 in 2004, what should be
his wage be in 2005.
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2004 inflation 2
2 of 300 6
His wage should be 300 6 306
27
Calculating Percentages
Measure of how much prices rise each year.
Int 2
Inflation
Inflation is normally given in percentage form
and is normally in the range 0 10
Example 2
In 2002 a CD cost 8. The cost increases in line
with inflation. What is the price in 2003 if
inflation is 1.5.
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2002 inflation 1.5
1.5 of 8 0.12
Price is 8 0.12 8.12
28
Calculating Percentages
Int 2
Now try MIA Ex 6 Ch2 (page 15)
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29
Calculating Percentages
Int 2
Reversing the change
Example 1
After a 10 increase the price of a house is 88
000. What was the price before the increase.
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30
Calculating Percentages
Int 2
Reversing the change
Example 2
The value of a car depreciated by 15. It is now
valued at 2550. What was its original price.
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31
Calculating Percentages
Int 2
Now try MIA Ex 7 Ch2 (page 17)
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