question_answer

The volume of the material of a hemispherical shell with outer and inner radii 9 cm and 7cm respectively is approximately

A)  808 cu cm       

B)  800 cu cm

C)  816 cu cm                   

D)  824 cu cm

Correct Answer: A

Solution :

Given that, Outer radius of hemispherical shell (R) = 9 cm and inner radius of hemispherical shell (r) = 7 cm \[\therefore \]Volume of a hemispherical shell \[=\frac{2}{3}\pi \,\,({{R}^{3}}-{{r}^{3}})=\frac{2}{3}\times \frac{22}{7}\times (729-343)\] \[=\frac{2}{3}\times \frac{22}{7}\times 386=\frac{16984}{21}=808.76\] \[\approx 808\]cu cm (approx.)