# You are given 500 grams of a substance with a half-life of 1.5 years. How much will remain after 15.0 years?

$0.488$ grams
$15.0$ years is $10$ times the half life, so the amount of the substance remaining will be:
(500"g")/2^10 = (500"g")/1024 ~~ 0.488"g"