Question

Please help with this growth/decay problem

Answer 1

How did that person get .85 for a?

Answer 2

http://oi50.tinypic.com/257oshv.jpg

Answer 3

N=No e^kt they have used 85 % of it so whats left is
No-0.15No=No e^1343k
No(1-0.15)=No e^1343k
0.85= e^1343k

Answer 4

Where does it say that they used 85?

Answer 5

what was left is 15% according to the prob

Answer 6

oh... okay I kind of understand. So if 20% of the sample decays, you would use .80 instead of .85?