Question 1079080
P=Poe^(-kt)
1/2=e^(-6k)
ln of both sides
-0.693=-6k
k=0.1155
0.12=e^(-.1155*t)
ln of both sides
-2.12=-.1155t
t=18.35 days.
Check.
half gone in 6 days
three-quarters gone in 12 days
seven-eights gone i 18 days. (0.125)