Digital SATMath: AlgebraEasy
A biologist is studying a bacterial culture. The number of bacteria, N(t), after t hours, is given by the function N(t) = 500 * (1.15)^t. What is the approximate number of bacteria after 4 hours?
- A575
- B1050
- C875
- D980
Show answer & explanationAnswer & explanation
Correct answer: C. 875
To find the number of bacteria after 4 hours, substitute t=4 into the given exponential function N(t) = 500 * (1.15)^t and calculate the result.
Why the other options are wrong
- A. This is 500 * 1.15, only for t=1, not t=4. Incorrect exponentiation.
- B. This might result from multiplying 500 by (1.15 * 4) instead of (1.15)^4.
- D. This might result from an arithmetic error or using an incorrect base for the exponent.
Evaluating Exponential Functions
Substituting a specific value for the independent variable into an exponential function to find the corresponding dependent variable value.
- The independent variable is typically in the exponent.
- Requires careful calculation of powers.
- Often used to model growth or decay over time.
Memory trick: Input time, get the growth number out.