The inner diameter of a circular building is 54 cm and the base of the

1.	The inner diameter of a circular building is 54 cm and the base of the wall occupies a space of 2464 cm2. The thickness of the wall is(a) 1 cm (b) 2 cm (c) 4 cm (d) 5 cm
Answer» (a) 1 cm Let the outer radius of the wall be R cm. Then, πR² = 2464 ⇒R² = \(\frac{2464\times7}{22}\) = 784 ⇒ R = \(\sqrt{784}\) = 28 cm. Inner diameter = 54 cm ⇒ Inner radius = 27 cm ∴ Thickness = 28 cm – 27 cm = 1 cm

The inner diameter of a circular building is 54 cm and the base of the wall occupies a space of 2464 cm2. The thickness of the wall is(a) 1 cm (b) 2 cm (c) 4 cm (d) 5 cm

Answer»

(a) 1 cm

Let the outer radius of the wall be R cm. Then,

πR² = 2464 ⇒R² = \(\frac{2464\times7}{22}\) = 784

⇒ R = \(\sqrt{784}\) = 28 cm.

Inner diameter = 54 cm

⇒ Inner radius = 27 cm

∴ Thickness = 28 cm – 27 cm = 1 cm