Problema Solution
Verla works in a medical laboratory. She is checking the effects of a certain antibiotic on a colony of bacteria to predict how well the antibiotic will treat an infection. If Verla estimates that there are 125,000 bacteria at 4 P.M., and the antibiotic kills half of the remaining bacteria every 12 hours, about how many bacteria should she expect to find at 10 A.M. the next morning?
Answer provided by our tutors
from 4 pm till 10 am next morning there are 18 hours
after 12 hours the number of bacteria will decrease by half:
(1/2)125,000 bacteria left
after another 6 hours = 6/12 = 1/2 of the time, there will be (1/2)(1/2) = 1/4 of the bacteria killed and 3/4 lefts or:
(3/4)*(1/2)*125000 = 46,875 bacteria left next morning.