Question

Tom wants to make a rocket model of the following dimensions.
Find the volume of this rocket model?

• A. $77\pi {\text{cm}}^3$
• B. $87\pi {\text{cm}}^3$
• C. $97\pi {\text{cm}}^3$
• D. $107\pi {\text{cm}}^3$

Answer 1

The correct option is B $87\pi {\text{cm}}^3$

Given,
The radius of a cone$=r=3$ cm
The depth of a cone $=h=5$ cm

As we know,
The volume of a cone $=\frac{1}{3}\pi r^{2}h$

$=\frac{1}{3}\pi \times 3^2\times 5$

$=\pi \times 3\times 5=15\pi {\text{cm}}^3$

Given,
The radius of a cylinder $=r=3$ cm
The depth of a cylinder $=h=8$ cm

As we know,
The volume of a cylinder $=\pi r^{2}h$
$=\pi \times 3^2\times 9=72\pi {\text{cm}}^3$

Total volume of a rocket model = Volume of cone + Volume of cylinder
$=15\pi {\text{cm}}^3+72\pi {\text{cm}}^3$
$=87\pi {\text{cm}}^3$