Question

question
which of the contexts below could be modeled by an exponential function?
answer
an elevator descends at a rate of 13 feet per second.
montraie puts $65 a month into a savings account.
a music service has a fixed monthly cost and charges $0.75 for each downloaded song.
a population of 200 bacteria triples every minute.

Explanation:

Exponential functions model quantities that change by a constant multiplicative factor over equal intervals, rather than a constant additive amount.

1. The elevator's descent is a constant rate (additive change per second), linear.
2. The fixed monthly cost plus per-song charge is a linear combination of fixed and variable additive costs.
3. The monthly savings deposit is a constant additive amount each month, linear.
4. The bacteria population triples (multiplicative factor of 3) every minute, matching exponential growth.

Answer:

A population of 200 bacteria triples every minute.