A certain antibiotic reduces the number of bacteria in your body by 10% each does. a)If four does of the antibiotic are taken, what percent of the original bacterial population is left?

Question

A certain antibiotic reduces the number of bacteria in your body by 10% each does. a)If four does of the antibiotic are taken, what percent of the original bacterial population is left?
I think the formula is supposed to be tn=100(9/10)^-1, but when i substituted 1 into it, the answer is wrong.

Emily · Answer

sorry i subbed 10 into it, and it was wrong.

Emily · Answer

sorry i meant 4

Reiny · Answer

It should be t(n) = 100(.9)^n so if n=4 t(4) = 100(.9)^4 = 65.61