Question

A hollow cylindrical tube 20 cm long, is made of iron and its external and internal diameters are 8 cm and 6 cm respectively. The volume of iron used in making the tube is $(\pi=\frac{22}{7})$

• A. 1760 cu.cm.
• B. 880 cu.cm.
• C. 440 cu.cm.
• D. 220 cu.cm.

Answer 1

Answer:

C. 440 cu.cm.

The volume of iron used $=\pi{r^2_1h}-\pi{r^2_2h}$

$=\pi{h{(r^2_1-r^2_2)}}$

$=\frac{22}{7}\times{20}(4^2-3^2)$

$=\frac{22}{7}\times{20}\times{7}=440$