Theory:

The diameter of an orange is \(7 \ cm\). Find the surface area of \(50\) oranges.
 
orange.png
 
Solution:
 
Diameter of an orange \((d)\) \(=\) \(7 \ cm\)
 
Radius of an orange \((r)\) \(=\) d2=72=3.5cm
 
Surface area of a sphere \(=\) \(4 \pi r^2\) sq. units
 
\(=\)  4×227×3.52
 
\(=\) 4×227×12.25
 
\(=\) \(154\)
 
Surface area of an orange \(=\) \(154\) \(cm^2\).
 
Surface area of \(50\) oranges:
 
\(=\) \(154 \times 50\)
 
\(=\) \(7700\)
 
Therefore, the surface area of \(50\) oranges is \(7700 \ cm^2\).
 
Important!
The value of \(\pi\) should be taken as \(\frac{22}{7}\) unless its value is shared in the problem.