Household smoke detectors contain 200μg of a radioactive element that has a half-life of 432 years. To the nearest 10μg, how much of this element will remain after 20 years?
a) 190 μg
b) 100 μg
c) 200 μg
d) 180 μg
1 answer
200 * 1/2^(20 / 432)