Acricket ball is dropped into a cylindrical tank of water.
the ball sinks to the bottom of the tank.
the diameter of the cricket ball is 7.2 cm
the diameter of the cylindrical tank is 15 cm
calculate the increase in height of the water in the tank.

* (in this question they didn't give me the volume of the cylinder or the height of the cylinder) -- the volume and height are NOT relevant. 

the ball is 7.2 cm in diameter. Hence its volume is 4*(3.6)^3 * π/3 
So, the volume the water occupies increases by this amount. 
because the tank is cylindrical, this increase must also be cylindrical. 
and the volume of the ïncreased cylinder is π*15^2 * h, where h is the increase in height of the water. 
so h = (4*(3.6)^3 * π/3)/(π*15^2) = 4*(3.6)^3/(3*15^2)

* (in this question they didn't give me the volume of the cylinder or the height of the cylinder) -- the volume and height is NOT relevant.

the ball is 7.2 cm in diameter. Hence its volume is 4*(3.6)^3 * π/3
So, the volume the water occupies increases by this amount.
because the tank is cylindrical, this increase must also be cylindrical.
and the volume of the ïncreased cylinder is π*15^2 * h, where h is the increase in height of the water.
so h = (4*(3.6)^3 * π/3)/(π*15^2) = 4*(3.6)^3/(3*15^2)

The only number less than 8 that can equal 12 would be 6, 36 is the dividend