Compound-interest rate sensitivity
Keep the $10,000 principal, $200 monthly end-of-period contribution, monthly compounding and 10-year term fixed. Change only the nominal annual rate.
| Scenario | Annual rate | Future value | Modeled growth |
|---|---|---|---|
| Lower-rate case | 3% | $41,441.82 | $7,441.82 |
| Base case | 6% | $50,969.84 | $16,969.84 |
| Higher-rate case | 9% | $63,216.43 | $29,216.43 |
The higher number is not automatically better evidence. Record why a rate belongs in the range and whether taxes, fees, volatility or changing contributions are excluded.
Break-even price sensitivity
Keep fixed costs at $120,000 and variable cost at $50 per unit. At prices of $70, $80 and $90, theoretical break-even volume changes because contribution margin changes. That relationship can support a pricing discussion, but it does not estimate demand.
| Price | Contribution margin | Break-even units |
|---|---|---|
| $70.00 | $20.00 | 6,000 |
| $80.00 | $30.00 | 4,000 |
| $90.00 | $40.00 | 3,000 |
Scenario discipline: change a defined assumption, preserve the rest of the model and explain the business reason for the range.