Question

You have 80 grams of tellurium how much will be left after 8 months if it’s half-life is 2 months?

Answer 1

5 grams.

Explanation:

First, find out how many half-lives have passed. Divide the number of months by the length of a half-life.

8÷2=4

4 half-lives have passed.

Now figure out how much tellurium will be left after 4 half-lives have passed. Multiply the starting amount of tellurium by
`(1)/(2)` a total of 4 times.

80 ·
`(1)/(2)`·
`(1)/(2)`·
`(1)/(2)`·
`(1)/(2)` = 5

That calculation could also be written with exponents

80 ·
`((1)/(2) )^(4)` = 5

After 4 half-lives, the amount of tellurium left will be 5 grams.