Question

question
which of the contexts below represents exponential growth?
answer
a music service has a fixed monthly cost and charges $0.65 for each downloaded song.
a towns population grows at a rate of 7.2% every year.
the amount of a certain medication in a person’s bloodstream decreases by \\(\frac{3}{5}\\) every week.
a radioactive compound decays at a rate of 26% per hour.

Explanation:

Exponential growth occurs when a quantity increases by a fixed percentage rate over time.

• The music service has a fixed cost plus a linear per-song charge, which is linear growth, not exponential.
• The medication amount decreases, which is exponential decay, not growth.
• The radioactive compound decays, which is exponential decay, not growth.
• The town's population increases by a fixed annual percentage rate, which fits the definition of exponential growth.

Answer:

A town's population grows at a rate of 7.2% every year.