Lesson Notes By Weeks and Term v4 - SHS 1
PROPORTIONAL REASONING
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PROPORTIONAL REASONING
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Subject: Mathematics
Class: SHS 1
Term: 1st Term
Week: 8
Grade code: 1.1.2.LI.2
Strand code: 1
Sub-strand code: 2
Content standard code: 1.1.2.CS.2
Indicator code: 1.1.2.LI.2
Theme: NUMBERS FOR EVERYDAY LIFE
Subtheme: PROPORTIONAL REASONING
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Proportional reasoning, especially using percentages, is one of the most practical mathematical skills we use every day. From the moment you buy waakye and notice the price has gone up, to when you save your pocket money in a susu box or a bank, you are dealing with percentage change and interest. Understanding these concepts helps us make smart financial decisions, understand the news about the economy, and manage our personal and future business finances effectively. This lesson will equip you with the tools to analyse and solve real-world problems involving money in our Ghanaian context.
This lesson focuses on three main applications of proportional reasoning: Percentage Change, Commercial Mathematics (Profit, Loss, Discount), and Simple Interest. Part A: Percentage Change (Increase and Decrease)
Percentage change measures how much a value has changed in relation to its original value. It is always expressed as a percentage.
i. Percentage Increase This is used when a quantity grows or increases in value. Examples include price hikes in fuel, an increase in school fees, or a rise in ECG bills.
Formula: `Percentage Increase = (Actual Increase / Original Amount) × 100%` Original Amount: The starting value before the change. Actual Increase: The difference between the new amount and the original amount (New Amount - Original Amount).