## anonymous 5 years ago suppose a radioactive isotope has a half- life of 82 years. If we currently have 80kg, how much will be left after 25 years?

1. anonymous

that's chemistry, hmm. is it a first level? second level?

2. anonymous

it second level If you could help me with it thank you very much cause i'm stuck

3. nowhereman

halflife of 82 years, means after $n \cdot 82\; \text{years}$ there is only an the $2^n$'th part left. So after x years there is $\frac{80\text{kg} }{2^{x/82\;\text{years}}}$ left.

4. anonymous

thank you my teacher told me to put it into the "pert" formula that's why i got confused could you help me put it into "pert" formula???? thanks

5. nowhereman

Sorry, I never heard of such a thing.

6. anonymous

it's okay thank you