Problem #77
Take a cylinder with a 50centimeter radius that is 100 centimeters
tall. Begin pouring water in. During the first three minutes, pour one
liter per minute [recall that a liter is 1000 cubic centimeters]. During
the second threeminute period, pour two liters per minute; during the
third threeminute period, pour three liters per minute, and so forth.

After 50 minutes, how deep will the water be?

How long will it take to fill the cylinder?
Source: An entrance exam for Azabu Junior High School in Tokyo