suppose that the amount in grams of a radioactive substance present at time t (in years) is given by A (t) = 160e-.70t. Find the rate of decay of the quantity present at the time when t = 4

Answer 1

A ' (t) = -.7(160) e^(-.7t)

so A ' (4) = -.7(160) e^-2.8
= -6.81

insert the units