7. Comparing Quantities

7. Comparing Quantities

Key Summary

This chapter explores the concepts of comparing quantities, including ratios, percentages, discounts, sales tax, and the basics of compound interest. It provides practical examples and exercises to help understand how to calculate these quantities in various scenarios, from everyday applications to financial calculations. Additionally, it emphasizes the importance of understanding percent changes in different contexts, such as population growth and depreciation.

Key Takeaways

  • Ratios express the relative size of two quantities.
  • Percentages provide a way to compare proportions within a whole.
  • Discounts and taxes directly impact the final price of goods and services.
  • Compound interest grows on the previously accrued interest, leading to exponential growth over time.

Key Concepts

  • Ratio: A comparison between two quantities showing how many times one value contains or is contained within the other.
  • Percentage: A fraction expressed as a part of 100, used to compare quantities relative to a total.
  • Discount: A reduction of the marked price of a product, often expressed as a percentage.
  • Sales Tax: A tax imposed on sales of goods and services, typically added to the final bill amount.
  • Compound Interest: Interest calculated on the initial principal, which also includes all accumulated interest from previous periods.