Find the volume of the cylinder and divide by 2.
V = pi * r^2 * h
Plug in what we know:
V = 3.14 * 2.5^2 * 10
V = 196.25
196.25 / 2 = 98.125
So the container contains 98.125 of face wash.
Now we divide this by 4 to see how many days it will last her.
98.125 / 4 = 24.53 = 25
So the face wash will last her about 25 more days.