Hi, I need some help setting up this problem properly

Problem:

After 23 days a 10-milligram sample of radioactive material decays to 5 milligrams. After how many days will there be 1 milligram of the material?

thanks!

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- Nov 8th 2006, 09:31 AMdibsHelp with setting up a problem
Hi, I need some help setting up this problem properly

Problem:

After 23 days a 10-milligram sample of radioactive material decays to 5 milligrams. After how many days will there be 1 milligram of the material?

thanks! - Nov 8th 2006, 09:50 AMtopsquark
where m(t) is the mass of the material at a given time t, is the initial amount of mass m(0), is the half-life, and t is the time elapsed.

So we know that

We need to solve this for .

/day

So

We wish to find out when m(t) = 1 mg.

Solve this like the preceding problem. I get days.

So 76.4 days or so.

-Dan - Nov 8th 2006, 11:00 AMdibs
thank you very much for the help!