Question 70

Radius of cross section of a solid right circular cylindrical rod is 3.2 dm. The rod is melted and 44 equal solid cubes of side 8 cm are formed. The length of the rod is (Take Π = 22/7)

Solution

Let length of cylindrical rod = $$h$$ cm and radius = $$r$$ = 3.2 dm = 32 cm

Edge of cube = $$a=8$$ cm

Volume of cylindrical rod = $$44 \times $$ Volume of cube

=> $$\pi r^2 h= 44 \times a^3$$

=> $$\frac{22}{7} \times (32)^2 h = 44 \times (8)^3$$

=> $$(32)^2 h=44 \times (8)^3 \times \frac{7}{22}$$

=> $$h=\frac{14 \times (8)^3}{(32)^2}$$

=> $$h=\frac{14}{2}=7$$ cm

=> Ans - (B)

Share on Whatsapp Share on Whatsapp

Create a FREE account and get: