Find the radius of a sphere whose surface area is 154 \({cm}^{2}\).

Let the radius of the sphere be r.
Given :
Surface area of sphere = 154 \( cm^2\)
\(\Rightarrow \) \(4 {\pi} {r}^2 = 154\) \({cm}^{2}\)
\(\Rightarrow \) \({r}^2 = \frac{154 × 7}{4 × 22}\) \({cm}^2\)
\(\Rightarrow \) \({r}^2 = \frac{7 × 7}{2 × 2} \) \({cm}^2\)
\(\Rightarrow \) \(r = \frac{7}{2} cm = 3.5 cm\)

\(\therefore \) the radius of the sphere whose surface area is 154 \({cm}^{2}\) is 3.5 cm.