Question

Jordan works in a science lab where he is studying the behavior of a certain unstable isotope. He has 240 milligrams of the sample, and the amount of the substance remaining in the sample decreases at a rate of 8% each day. After t days, there are less than 115 milligrams of the substance remaining. Which inequality represents this situation, and after how many days will the amount of the sample be less than 115 milligrams?

Answer 1

Answer:

A = A0 (.92)^t

A / A0 = 115 / 240 = .479

ln .479 = t ln .92

t = .736 / .0834 = 8.83

After 9 days there will be less than 115 mg