Math/pre-calc Decay Rate Question

Question

Radioactive substance: Polonium

Decay Rate, k: ___% per minute

Half life, T: 44.6 Minutes

Answer 1

A=Pe^-44.55r

1/2 =e^-44.55r

-44.55r = ln.5

r= ln.5/-44.55

r= .015576 = 1.5576% decay rate per minute, given the info provided

but Polonium 210 is known for 140 day half life, not 44.55 minutes

and Polonium 215 has half life of .0018 seconds

so your Polonium must be an isotope somewhere between 210 and 215