Answer:
62.17 days
Explanation:
The computation of the number of days is shown below:
Given that
A(t)=10 × 0.5^(t ÷ 18.72)
1 = 10 × 0.5 ^ (t ÷ 18.72)
0.1 = 0.5 ^ (t ÷ 18.72)
Now consider the log in both sides
ln(0.1) = ln(0.5)^ (t ÷ 18.72)
ln(0.1) ÷ ln(0.5) = (t ÷ 18.72)
3.321928095 = (t ÷ 18.72)
So, t = 62.17 days
With the help of log, we can easily compute it