Answer to Question #123358 in Physics for Treasure

Question

•The half-life period of yttrium is 20 min. If there are 1000 g of yttrium present, how much will be left after 30 min?

Answer 1

$$m=M\cdot 2^{-\frac{t}{T}}\\m=1000\cdot 2^{-\frac{30}{20}}=354\ g$$