SATMediumFrequency: 2 - 3 questions
Exponential Growth, Decay, & Percent Change
Exponential models follow the general formula y = a(1 + r)^t for growth and y = a(1 - r)^t for decay, where a is the initial value, r is the rate of change per unit t, and (1 ± r) is the growth/decay factor.
Core Formula & Concept Cheat Sheet
1y = a(1 + r)^t (Growth)
2y = a(1 - r)^t (Decay)
3Half-life: y = a(1/2)^(t / k)
The 700+ Score Trap
Confusing percent decrease with remaining amount (e.g. 15% decrease means multiply by 0.85, not 0.15).
Test Your Mastery
Official Exam FormatLive Interactive Practice Drill
A sample of radioactive isotope decays at an annual rate of 14%. If the initial mass was 250 grams, which function models mass M(t) remaining after t years?
Frequently Asked Questions
How do I recognize an exponential function versus a linear function?
Linear changes by a constant difference (+d); exponential changes by a constant factor or percentage (×r).