Simple interest — Study Path Agent

Chapter 1

Core concepts & vocabulary

1

Principal, interest, rate, time (P, I, r, t)

2

Simple vs. compound interest (what changes and why)

3

Percent, decimal, and basis points conversions

4

Units and timelines (days, months, years)

5

Interpreting rate statements (APR, “per year”, “per month”)

Chapter 2

Simple interest formulas & rearrangements

6

Derive and use I = P·r·t

7

Total amount (future value) A = P + I = P(1 + r·t)

8

Solve for principal P given A, r, t

9

Solve for rate r given P, I (or A), t

10

Solve for time t given P, I (or A), r

11

Check answers with estimation and reasonableness tests

Chapter 3

Time conventions & rate conversions

12

Convert percent rate to decimal rate (and back)

13

Convert between annual and monthly rates (simple proportional conversion)

14

Convert months/weeks/days to years (t in years)

15

Day-count basics: 30/360 vs actual/365 (when each is used)

16

Partial periods and odd days problems

17

Common pitfalls: mixing units (months with annual rate, etc.)

Chapter 4

Applied simple-interest problems

18

Bank loans: compute interest and payoff amount

19

Promissory notes and short-term lending (maturity value)

20

Savings/investments with simple interest (future value)

21

Discounting back to present value with simple interest

22

Simple interest word-problem translation (identify P, r, t)

23

Multi-step problems (fees, partial payments, changing time periods)

24

Practice set: 15 mixed problems (self-check)

Chapter 5

Representation & intuition

25

Linear growth model: interest earned grows proportionally with time

26

Graph A(t) and I(t) as straight lines; interpret slope

27

Compare scenarios: changing P vs changing r vs changing t

28

Back-of-the-envelope estimation (e.g., 10% for 3 years ≈ 30%)

29

Explain results in plain language (what the numbers mean)

Chapter 6

Tools, calculators, and checking work

30

Calculator workflow (order of operations, rounding strategy)

31

Spreadsheet setup (cells for P, r, t; compute I and A)

32

Excel/Google Sheets formulas (e.g., =P*r*t and =P*(1+r*t))

33

Common rounding and currency formatting rules

34

Self-audit checklist for simple-interest problems