Question

Question 16..........

Answer 1

Since the diameter is 6 cm, the radius is 3 cm. Use the area formula to get 113.04 cm squared. Then, you multiply that by the height of the rod, which is 20 cm. The volume of one rod is 2260.8 cm cubed. To find how much steel is needed for 189 rods, multiple the volume of one rod by 189. Your answer should be 427291.2 cm³.

Answer 2

If the cylinder-shaped rods are solid (not hollow), then the amount of steel needed to make a rod is the same as the volume of the rod. Multiply that by 189 to get the amount of steel needed to make 189 rods.
Area of a cylinder = pi*r*r*h
r = diameter/2 = 6/2 = 3
h = 20
Area=189(pi*3*3*20)=189(pi*180)
The question says to use 3.14 as pi, so:
189(pi*180)=189(3.14*180)=189(565.2)=106822.8
A cylinder is three dimensional so the unit is cm^3
Answer: 106822.8 cm^3
565.2*189