When doctors prescribe medicine, they must consider how the drug’s effectiveness declines as time passes. If each hour a drug is only 90% as effective as the previous hour, at some point the patient will have to be given another dose in order for the drug to remain effective. If the initial dose was 500 mg and the drug was administered 6 hours ago, how long will it take for the initial dose to reach a level of 150 mg?
This is an example of
A) exponential growth.
B) exponential decay.
C) quadratic growth.
D) logistic decay.