How much is in 60 days?

Question

Iodine-125 decays at a regular and consistent exponential rate. The half-life of Iodine-125 is approximately 60 days. If we have 40 grams of Iodine-125 today, how much is left in 60 days?

Answer 1

Half-life is the time its takes for half of the Iodine to go away.

A half-life of 60 days means that after 60 days half has gone away.

If you start with 40 how much goes away in 60 days