Help AGAIN

1. Apr 25, 2006

beanryu

In 440 days, an unknown radioactive substance decays to 30 percent of its original amount.

(a) What is the constant k in the form of solution y(t) = Aexp(kt)?

k=?

First of all.... I dont even know what Aexp(kt) mean

does it A^(kt) or what?!

2. Apr 25, 2006

dav2008

It means $$y(t)=Ae^{kt}$$