math
posted by Melissa .
a certain antibiotic redues the number of bacteria in your body by 10% each dse, if 4 doses of the antibiotic are taken, what percent of the original bacterial population is left

after 1st day .9 or 90% left
after 2nd day .9^2 or .81 or 81% left
after 3rd day .9^3 .......
etc