Question

Radium decays according to the function where Q represents the quantity remaining after t years and k is the decay constant 0.00043. How long will take for 40g of radium to decay to 10g?

Answer 1

For this problem, we use the formula for radioactive decay which is expressed as follows:

An = Aoe^-kt

where An is the amount left after time t, Ao is the initial amount and k is a constant.

We calculate as follows:
An = 10 g

Ao = 40 g
k = 0.00043

An = Aoe^-kt
10 = 40e^-0.00043(t)
t = 3223.94 years