# Math Help - Differntial Problem Radioactive decay

1. ## Differntial Problem Radioactive decay

A sample of 100g (intially) of pure Bismuth-210 contains only 14.4 g of the radioactive substance after 14 days. Determine the mass m(t) of bismuth-210 after t days and the half-life of bismuth-210.
Any help will be much appreciated! thanx

2. $y = y_0e^{kt}
$

general equation is $y = 100e^{kt}$

$14.4 = 100e^{k \cdot 14}$

solve for k.

use the equation and the value of k found above ...

$50 = 100e^{kt}$

and solve for t to find the half-life