Question

If CSA of a sphere is 154 $c{m}^2$, then its radius is cm.

• A. 7
• B. 4.5
• C. 3.5

Answer 1

Answer: (A), (C)

The correct options are
A 7
C 3.5

CSA of sphere = 4πr${}^2$
$\Rightarrow 154=4\times \frac{22}{7}\times r^2$
$\Rightarrow r^2=\frac{154\times 7}{88}$
$\Rightarrow r^2=\frac{49}{4}$
$\Rightarrow r^2=(\frac{7}{2}{)}^2$
$\Rightarrow r=\frac{7}{2}$

Thus, r = 3.5 cm