Math 1 · Unit 8 · Lesson 5 · part 1 of 5
The Words We Use
The vocabulary for this lesson, in one place.
Words we use
| Word | Plain English | What you do |
|---|---|---|
| Depreciation | Losing value over time. | Same form as compound interest, with a factor below 1. |
| Decay factor | 1 minus r: the number you multiply by each time. | Losing 13% gives 0.87. |
| Decay rate | r, the percent lost each time. How far the factor is below 1. | A factor of 0.85 is a rate of 15%, not 85%. |
| Doubling time | How long it takes an amount to double. | Find it with a table. 72 divided by the rate is a quick estimate. |
| Principal, balance | The starting amount and the amount now. On a loan, what you borrowed and what you owe. | Interest on a debt grows the same way savings do. |
| Growth factor | 1 plus r, from Lesson 2. | Above 1 grows, below 1 shrinks, exactly 1 does nothing. |