Guys, could you please help me with this problem?

"The half-life of a radioactive substance is 250 years. What fraction of a certain amount of the substance will remain after 1500 years?"

Is there a formula I need to use?

Thanks a bunch..

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- Aug 6th 2008, 07:50 PMc47v3770Half-life problem. Please help :)
Guys, could you please help me with this problem?

"The half-life of a radioactive substance is 250 years. What fraction of a certain amount of the substance will remain after 1500 years?"

Is there a formula I need to use?

Thanks a bunch.. - Aug 6th 2008, 07:56 PMmr fantastic
- Aug 6th 2008, 08:01 PMChris L T521
The formula for radioactive decay is , where is the initial amount of a substance, is the amount of a substance after t years, and is the decay constant.

The decay constant can be found using the half life formula

So we see that

Thus, our equation would be

After 1500 years, we have

Thus, the amount of substance remaining after 1500 years will be of the original substance.

Does this make sense? If you have a question, feel free to ask. We're here to help you.

--Chris