Here, inner radius (r) = 24/ 2 cm = 12 cm
Outer radius (R) = 28/ 2 cm = 14 cm, h = 35 cm
Volume of the wood used in the pipe = π(R2 – r2) h
= 22/ 7 [(14)4 – (12)2] × 35 cm3
= 22/ 7 × 26 × 2 × 35 cm3 = 5720 cm3
Mass of 1 cm3 of wood = 0.6 g
∴ Mass of 5720 cm3 of wood = 0.6 × 5720 g = 3432 g = 3.432 kg Ans.