Question

Kelli's mom takes a 520 mg does of aspirin. Each hour, the amount of aspirin in a person's body system decreases by about 22%. After at least how many hours will the amount of aspirin in her body be less than 80 mg?

Answer 1

Answer:

we can write an equation wich describes the amount of aspirin in her system in respect to the hours (x)

a(x) = 520 * 0.78^x

78% is what's left on respect to one hour before and the "to the power of x" part describes how often we multiply/how many hours have passed

actually, if you haven't learned a better method yet, you could just grab your calculator, and type in 520 * 0,78

calculate it

then repeat multiplying the last answer till you go just below 80. the number of steps is the number of full hours passed.

this would take 8 steps

do you need a more sophisticated method to nail it down to the minute?

got no clue how far you are with the whole topic yet.

anyways, hope this helps you :)