Question

question
which of the contexts below represents exponential decline or decay?

answer
the amount of a certain medication in a persons bloodstream decreases by \\(\frac{2}{5}\\) every day.
snow was melting at a rate of 2.5 inches per hour.
a coin collection appreciates at a rate of 2.4% per year.
a population of 250 bacteria doubles every month.

Explanation:

Exponential decay is a process where a quantity decreases by a constant proportion over equal time intervals.

1. Medication in bloodstream: Decreases by a fixed fraction ($\frac{2}{5}$) daily, which fits exponential decay.
2. Snow melting: Decreases by a fixed amount (2.5 inches) hourly, this is linear decay, not exponential.
3. Coin collection: Increases in value, this is exponential growth.
4. Bacteria population: Doubles monthly, this is exponential growth.

Answer:

The amount of a certain medication in a person's bloodstream decreases by $\frac{2}{5}$ every day.