What you’ll learn
Model exponential decay.
Key idea
The decay factor is the part retained after subtracting the loss fraction from a whole.
Use the fraction remaining, not the fraction lost; percent loss does not mean fixed absolute subtraction.
Worked example
Enter the exact value or ordered values in the format requested below.
A measured quantity P starts at 150 units at t=0, loses 40% of its CURRENT amount after each whole period; t is a nonnegative integer. Write the complete model P in terms of t.
- The retained fraction is 1-0.4=0.6, strictly between zero and one.
- P=150(0.6)^t gives 150 initially and 90.0 after one period; multiply the remaining amount by 0.6 at each next period.
Answer: P=150(0.6)^t
Quick Check
Choose which candidate representation satisfies the requirements of 'Model exponential decay' and justify the choice.
A measured quantity P starts at 350 units at t=0, loses 5% of its CURRENT amount after each whole period; t is a nonnegative integer. Choose with starting-value AND retention evidence.