The half-life of radium – 226 is 1590 years. If a sample contains 300 mg, how many milligrams will remain after 2000 years?

Answer 1

Hello Perla,

One formula you may have seen in your class is:

a_n = a₀ * (1/2)^{time/half_life}

It translates to this: (final amount) = (initial amount)* (1/2)^{time/half_life}

You're given:

initial amount = 300 mg

half-life = 1590 years

time = 2000 years

Plug them into the formula: (final amount) = 300 * (1/2)^2000/1590

Run it on a calculator, and you should get a final amount of 125.45 mg.