Answer with Explanation:
External radius = 4 cm,
Internal radius = 3 cm.
Volume of iron
= (22/7 x [(4)2 - (3)2] x 21) cm3
= (22/7 x 7 x 1 x 21)cm3
= 462 cm3.
Therefore, Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.
External radius = 4 cm,
Internal radius = 3 cm.
Volume of iron
= (22/7 x [(4)2 - (3)2] x 21) cm3
= (22/7 x 7 x 1 x 21)cm3
= 462 cm3.
Therefore, Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.