# Math Help - Exponential Decay/and growth question involving half life.

1. ## Exponential Decay/and growth question involving half life.

A 200 gram sample of compound XYZ has a half life of 304 hours.

a.) state the decay/growth factor.
b.) write an exponential equation that models this scenario.
c.) Calculate how many grams of the sample will be left after 60 days to the nearest 100th of a gram.

Please solve and explain. I have a quiz on this tomorrow.

2. ## Re: Exponential Decay/and growth question involving half life.

Originally Posted by Nabilrahman16
A 200 gram sample of compound XYZ has a half life of 304 hours.

a.) state the decay/growth factor.
b.) write an exponential equation that models this scenario.
c.) Calculate how many grams of the sample will be left after 60 days to the nearest 100th of a gram.

Please solve and explain. I have a quiz on this tomorrow.

$y = 200\left(\frac{1}{2}\right)^{k_1 \cdot t}$

$100 = 200\left(\frac{1}{2}\right)^{k_1 \cdot \frac{38}{3}}$

solve for $k_1$ and you have your decay function.

or ...

$y = 200e^{k_2 \cdot t}$

$100 = 200e^{k_2 \cdot \frac{38}{3}}$

solve for $k_2$, same idea.