math
posted by kolapo .
a solid alumimium casting for a pulley consists of the discs each 1 1/2 cm thick of diameters 4 cm, 6 cm,and 8 cm.a central hole 2 cm in diameter is drilled out .if the density of the alumimium is 2.8g/cm^3,calculate the mass of the casting

I see a volume of
π(2^2)(1.5) + π(3^2)(1.5) + π(4^2)(1.5)  π(1^2)(4.5)
then multiply that result by 2.8 to get the mass in grams