### Theory:

The diameter of an orange is $$7 \ cm$$. Find the surface area of $$50$$ oranges.

Solution:

Diameter of an orange $$(d)$$ $$=$$ $$7 \ cm$$

Radius of an orange $$(r)$$ $$=$$ $\frac{d}{2}=\frac{7}{2}=3.5\phantom{\rule{0.147em}{0ex}}\mathit{cm}$

Surface area of a sphere $$=$$ $$4 \pi r^2$$ sq. units

$$=$$  $4×\frac{22}{7}×{\left(3.5\right)}^{2}$

$$=$$ $4×\frac{22}{7}×12.25$

$$=$$ $$154$$

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.