Question 136

A cylinder 84 cm long is made of steel. Its external and internal diameters are 10 cm and 8 cm respectively. What is the volume of the steel in the cylinder (in $$10^{-3}m^3$$ and correct up to three decimalplaces)?

Solution

External radius = $$R=5$$ cm and internal radius = $$r=4$$ cm

Volume of steel = $$\pi R^2h-\pi r^2h$$

= $$\pi h(R^2-r^2)$$

= $$\frac{22}{7}\times84(5^2-4^2)$$

= $$264\times9=2376$$ $$cm^3$$

= $$2.376\times10^{-3}$$ $$cm^3$$

=> Ans - (B)

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