decay given by A(t) = 831 e-0.02t; find amt left after 65 yr

[charlesjoy]

The decay of 831 mg of an isotope is given by A(t)=831e-0.02t, where t is the time in years. Find the amount left after 65 years.

Answer is either 222, 226, 113 or 815. (Need to understand logic on doing this problem)

 

[BigGlenntheHeavy]

Re: Show me how to figure out this problem

A(t) = 831e^-.02t, A(65) = 831e^[(-.02)(65)] = 226.4739...

 

[charlesjoy]

Thank you.