A rectangular tank with base 40 cm by 22 cm holds some water. A solid metal cylinder of radius 7 cm and height 10 cm is lowered in until it is completely under water. Find the rise in the water level, in cm. Take π = 22/7.

The water rises by exactly the volume of the sunken cylinder: $(22/7)\times 49\times 10=1540{\text{cm}}^3$. The tank's base area = $40\times 22=880{\text{cm}}^2$, so the rise = 1540/880 = 1.75 cm. (Using the diameter 14 cm as the radius makes the cylinder four times as big and gives 7 cm; dividing by 88 instead of 880 gives 17.5 cm and dividing by 8800 gives 0.175 cm.)