SAT Math: Modeling Exponential Growth
42+ practice questions in Praczo
The concept, explained
- 1
Exponential models take the form y = a * b^x, where "a" is the initial amount and "b" is the growth/decay factor.
- 2
If something grows by a percentage (like 5% per year), the growth factor "b" is 1 + r (1 + 0.05 = 1.05).
- 3
If something decays by a percentage (like losing 20% a year), "b" is 1 - r (1 - 0.20 = 0.80).
- 4
Look out for phrases like "doubles automatically". If it doubles, b=2. If it halves, b=0.5.
- ✗ Using an additive rate of change (like a linear model mx + b) instead of a multiplicative factor when dealing with percentages.
- ✗ Using 0.05 as the base for 5% growth instead of 1.05 (multiplying by 0.05 means you only KEEP 5%, losing 95%).
SAT-style practice
A rare painting is purchased for $10,000 and appreciates in value by 4% each year. Which equation models its value V after t years?
Ready to master this concept?
Praczo tracks your mastery on all 179 SAT concepts — not just broad topics. One sample question is a start; drilling to mastery is how scores move.
3-day free trial — no credit card required