# Thread: need you HELP guyz ^^

1. ## need you HELP guyz ^^

A steel drum in the shape of a right circular cylinder is required to have a volume of 1,000,000 cubic centimeters. the top and bottom are made up of material that costs P8.00 (8 pesos) per square centimeter, while the sides are made up of material that costs P3.00 (3 pesos) per square centimeter.

a.) Express the total cost C of the materials as a function of the radius r of the cylinder.

b.) What is the cost if the readius is 40 cm? (use ∏= 3.14 )

2. Originally Posted by dartanian24
A steel drum in the shape of a right circular cylinder is required to have a volume of 1,000,000 cubic centimeters. the top and bottom are made up of material that costs P8.00 (8 pesos) per square centimeter, while the sides are made up of material that costs P3.00 (3 pesos) per square centimeter.

a.) Express the total cost C of the materials as a function of the radius r of the cylinder.

b.) What is the cost if the readius is 40 cm? (use ∏= 3.14 )
$\pi r^2 h = 10^6$

$h = \frac{10^6}{\pi r^2}$

$C = 8(2\pi r^2) + 3(2\pi r h)$

substitute the expression for $h$ into the cost equation, then answer the questions.