SSC Sample Paper Mock Test-11 SSC CGL Tear-II Paper-1

The radius and the slant height of a cone are in the ratio of 4 : 7. If its curved surface area is \[792\,\,c{{m}^{2}}.\]Then, the radius is

A) 10 cm

B) 11 cm

C) 12 cm

D) 13 cm

Correct Answer: C

Solution :

Let radius = 4x cm

Slant height = 7x cm

Curved surface area = 792 (Given)

\[\therefore \]\[\frac{22}{7}\times 4x\times 7x=792\]

\[\Rightarrow \] \[88{{x}^{2}}=792\]\[\Rightarrow \]\[{{x}^{2}}=\frac{792}{88}=9\]\[\Rightarrow \]\[x=3\]

\[\therefore \]Radius of cone \[=4x=4\times 3=12\,\,\text{cm}\]