Question

An iron pillar has some part in the form of a right circular cylinder and remaining in the form of a right circular cone. The radius of base of cone, as well as cylinder is 21 cm. The cylindrical part is 80 cm high and conical part is 16 cm high.
Find the weight of the pillar, if 1 cm3 of iron weighs 8.45 g :

• A. 999.39 kg
• B. 111 kg
• C. 1001 kg
• D. 989 kg

Answer 1

The correct option is A 999.39 kg


Total volume $=\pi r^2{h}_1+\frac{1}{3}\pi r^2{h}_2=\pi r^2[h_1+\frac{h_2}{3}]=\frac{22}{7}\times (21{)}^2[80+\frac{16}{3}]=\frac{22}{7}\times 441\times \frac{256}{3}$
$Totalweight=\frac{22}{7}\times 441\times \frac{256}{3}\times \frac{8.45}{1000}=999.39kg$