Question

The half-life of a radioactive kind of iodine is 60 days. How much will be left after 240 days, if you start with 480 grams of it?

Answer 1

30 grams

Explanation:

half life is 60 days so every 60 days the amount 480 grams will be half

in 240 days will decay 240 /60 = 4 times

once 480 /2 = 240

twice 240 /2 = 120

trice 120 / 2 = 60

four times 60/2 = 30 grams will be left