In a toy factory 200 wooden solid cylinder 7cm long and 35mm in diameter have to be painted. What is the total surface area in cm^2 that needs to be painted?

The surface area of a cylinder is:

A=2pr^2+2prh and since r=d/2

A=2p (d^2/4+dh/2)

A = (p/2) (d^2+2dh) and we need 200 of these cylinders ...

A = (100p) (d^2+2dh), and using d and h, 3.5cm and 70cm we get:

A = (100p) (3.5^2+2*3.5*7)

A = (100p) (12.25+49)

A=6125p cm^2

A≈19242 cm^2 (to nearest cm^2)