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Financial Literacy
Grade 8-12
Inflation & Purchasing Power Cheat Sheet
A printable reference covering inflation rate, purchasing power, CPI, real income, nominal income, and cost-of-living changes for grades 8-12.
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Inflation measures how prices change over time and how those changes affect what people can buy. This cheat sheet helps students connect everyday prices, wages, savings, and budgets to purchasing power. It is useful for comparing costs across years and understanding why money may buy less in the future.
Key Facts
- Inflation rate = (new price index - old price index) / old price index × 100%.
- Purchasing power means how much goods and services a certain amount of money can buy.
- If prices rise and income stays the same, purchasing power decreases.
- Real income = nominal income / price index × 100 when the price index uses 100 as the base year.
- A price index compares the cost of a basket of goods in one year to the cost in a base year.
- Cost after inflation = original cost × (1 + inflation rate) when the inflation rate is written as a decimal.
- Real interest rate ≈ nominal interest rate - inflation rate.
- Deflation means the overall price level decreases, so each dollar may buy more than before.
Vocabulary
- Inflation
- Inflation is a general increase in prices across an economy over time.
- Purchasing Power
- Purchasing power is the amount of goods and services that money can buy.
- Consumer Price Index
- The Consumer Price Index, or CPI, is a measure of average price changes for a common basket of consumer goods and services.
- Nominal Income
- Nominal income is income measured in current dollars without adjusting for inflation.
- Real Income
- Real income is income adjusted for inflation to show actual buying power.
- Cost of Living
- Cost of living is the amount of money needed to pay for basic expenses such as housing, food, transportation, and utilities.
Common Mistakes to Avoid
- Confusing nominal income with real income is wrong because a higher paycheck does not always mean greater buying power if prices rise faster.
- Using a percent as a whole number is wrong because 4% must be written as 0.04 in formulas such as cost after inflation = original cost × 1.04.
- Assuming all prices rise by the same amount is wrong because inflation is an average and individual items can rise, fall, or stay the same.
- Ignoring the base year in a price index is wrong because index values only make sense when compared to the base year value of 100.
- Thinking inflation always means people are poorer is wrong because incomes, savings interest, and benefits may also change over time.
Practice Questions
- 1 A movie ticket cost 11 this year. What is the inflation rate for the ticket price?
- 2 A student earns $200 per month. If prices rise by 5% and income stays the same, what is the approximate loss in purchasing power compared with last year?
- 3 An item costs $80 today. If inflation is 3% for one year, what is the expected cost next year?
- 4 A worker receives a 4% raise during a year when inflation is 6%. Explain whether the worker's purchasing power increased or decreased.