Question : From a solid right circular cylinder of length 4 cm and diameter 6 cm, a conical cavity of the same height and base is hollowed out. The whole surface of the remaining solid (in square cm) is:
Option 1: 48$\pi$
Option 2: 15$\pi$
Option 3: 63$\pi$
Option 4: 24$\pi$
Latest: SSC CGL preparation tips to crack the exam
Don't Miss: SSC CGL complete guide
Correct Answer: 48$\pi$
Solution :
Given: Diameter = 6 cm
So, radius, $r$ = $\frac{6}{2}$ = 3 cm
Height, $h$ = 4 cm
$\therefore$ Curved surface area of the cylinder $=2\pi rh=2\pi×3×4=24\pi$
Now, slant height, $l$ = $\sqrt{r^2+h^2}$ = $\sqrt{3^2+4^2}$ = $5$
So, the curved surface area of the cone $=\pi rl=\pi×3×5=15\pi$
Area of the circle on the top $=\pi r^2=\pi×3^2=9\pi$
Required whole surface area
= curved surface area of cylinder + curved surface area of cone + area of the circle
= $24\pi+15\pi+9\pi$
= $48\pi$
Hence, the correct answer is 48$\pi$.
Related Questions
Know More about
Staff Selection Commission Combined Grad ...
Answer Key | Eligibility | Application | Selection Process | Preparation Tips | Result | Admit Card
Get Updates Brochure
Your Staff Selection Commission Combined Graduate Level Exam brochure has been successfully mailed to your registered email id “”.
