The radii of the ends of a frustum of a cone 7 cm high are 5 cm and 3 cm. Find its volume correct to one decimal place. (use \(\pi = \frac{{22}}{7}\))

Question

Question

This question was previously asked in

SSC CGL 2022 Tier-I Official Paper (Held On : 12 Dec 2022 Shift 2)

Answer 1

Given:

The radii of the ends of a frustum of a cone 7 cm high are 5 cm and 3 cm.

Concept used:

Volume of a frustum of cone = \(\frac {\pi H}{3} \times ({R^2 + r^2 + Rr})\) (R = Radius of the base, r = Radius of the high and H = Height)

Calculation:

Now, the volume of the frustum of the cone

⇒ \(\frac {\frac {22}{7} \times 7}{3} \times ({5^2 + 3^2 + 5 \times 3})\)

⇒ \(\frac {22}{3} \times 49\)

⇒ 359.333 ≈ 359.3 cm3

∴ Its volume is 359.3 cm3.

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