Model 3: Two-Condition Comparison

04 Try it yourself Interactive

Two amounts in, principal and rate out

Set an amount at one time and a larger amount at a later time. The console subtracts, divides down to a single year, walks backwards to the principal and then reads the rate off it. Watch the second step: that is where the principal disappears, and everything after is arithmetic.

13,000 at 4 yr → 19,500 at 9 yr

P = 7,800 · R = 16.67%

The later time must carry the larger amount — a sum at simple interest never shrinks. Impossible pairs are refused rather than answered.

Press Next to work through it one step at a time.

Interest gap–

Per year–

Principal–

Rate–

step 0 / 0