Question 1048185
(93.75% loss is 15/16) but we will ignore that until checking.
A=Ao^e^kt
A/Ao=1/2-e^(-kt)
ln of both sides
-0.693=-k(3.634)
minus signs divide out
k=0.1907
A=Ao*e(-0.1907)
A/Ao=0.0625=e^(-0.1907t)
ln of both sides
-2.7726=-0.1907t
divide by -0.1907
t=14.54 days
Check
This is 4 half-lives, which is 14.546 days.