Question 972051
f(5)=100*2^-(5/5)=50  That is just 1 half life and it is 100*2^-1 or 100/2
f(10) is two half-lives, or half of a half.  That is 25.

f(12.5) is 100*2^-(2.5)=17.68 mg

{{{graph (300,300,0,15,0,100,100*2^(-x/2))}}}   y-axis by 10s; x-axis by 1 day