Answer: The thickness of his pencil holder would be 1 cm.
Step-by-step explanation:
Since we have given that
Volume of lump of clay = 200 cubic cm
Height of pencil holder = 9 cm
Radius of pencil holder = 3 cm
Let the thickness of pencil holder be 'x'.
As we know the formula for "Volume of pipe":
[tex]Volume=\pi (R^2-r^2)h\\\\200=\dfrac{22}{7}(R^2-9)\times 9\\\\1400=22\times 9(R^2-9)\\\\1400=198(R^2-9)\\\\\dfrac{1400}{198}=R^2-9\\\\7.07+9=R^2\\\\16.07=R^2\\\\R=\sqrt{16.07}\\\\R=4.008\\\\R\approx 4[/tex]
Since x = R-r
x = 4-3
x=1 cm
Hence, the thickness of his pencil holder would be 1 cm.