Question

The function Q(t)=Qe^-kt may be used to model radioactive decay. Q represents the quantity remaining after t years; k is the decay constant, 0.00011. How long, in years, will it take for a quantity of plutonium-240 to decay to 25% of it's original amount?

Answer 1

12,600 years

Explanation:

Answer 2

It will take 12602.68 years.

Solution:
Q(t)=Qe^-kt
Q(t)=0.25Q
0.25Q=Qe^-0.00011t
ln 0.25=-0.00011t
t=(ln 0.25)/-0.00011= 12602.67601