For finding the strength of the capsules after one year, we will use half-life formula. The formula is:
A = A₀
where, A= Final amount
A₀ = Initial amount
t= time elapsed
h= half-life
Here, in this problem A₀ = 10000 milligram, t= 1 year or 365 days
and h= 28 days
So, A = 10000
⇒ A = 10000
⇒ A = 1.187
So, the strength of the capsules after one year will be 1.187 milligrams.