Question

Metallic cylinder has a radius 3 cm and height 5cm reduces weight the conical hole is drilled in a cylinder has a diameter of radius 20 cm the ratio of the volume of them

Answer 1

Ok, here's what you want.

the metallic cylinder's specifications are here.

r₁=3 cm

h₁=5 cm

Now we know that the conical hole is also cylindrical, and the height of it is 8/9 cms and the radius is 3/2 cms. 

so, for the hole...

r₂=3/2=1.5 cm

h₂=8/9 cm

then let's find the area of the metallic cylinder, which is πr₁²h

so, πr₁²h₁= (22/7) (3)² (5)

           A₁ =141.428

           A₁ ≈141.43 cm²

and for the hole....

 πr₂²h₂= (22/7) (1.5)² (8/9)

      A₂ = 6.2857

      A₂ ≈ 6.29 cm²

all we have to do is to conclude the volume of the hole from the cylinder , and that is...

A₁-A₂

=141.43 - 6.29 

=135.14 cm²

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