The following table shows the number of patients of different age group who were discharged from the hospital in a particular month: Find the 'mean'…

Age (in years)	Number of patients \(\displaystyle \left(f_{i}\right)\)	Class Mark \(\displaystyle \left(x_{i}\right)\)	\(\displaystyle f_{i} x_{i}\)
$\displaystyle 5$-$\displaystyle 15$	$\displaystyle 6$	$\displaystyle 10$	$\displaystyle 60$
$\displaystyle 15$-$\displaystyle 25$	$\displaystyle 11$	$\displaystyle 20$	$\displaystyle 220$
$\displaystyle 25$-$\displaystyle 35$	$\displaystyle 21$	$\displaystyle 30$	$\displaystyle 630$
$\displaystyle 35$-$\displaystyle 45$	$\displaystyle 23$	$\displaystyle 40$	$\displaystyle 920$
$\displaystyle 45$-$\displaystyle 55$	$\displaystyle 14$	$\displaystyle 50$	$\displaystyle 700$
$\displaystyle 55$-$\displaystyle 65$	$\displaystyle 5$	$\displaystyle 60$	$\displaystyle 300$
Total	\(\displaystyle \sum f_{i}=80\)		\(\displaystyle \sum f_{i} x_{i}=2830\)

\[\begin{aligned} \text { Mean } & =\frac{2830}{80} \\ & =\frac{283}{8} \text { or } 35.38 \text { years } \end{aligned} \] Modal class is $\displaystyle 35$-$\displaystyle 45$ \[\begin{aligned} \text { Mode } & =35+\frac{23-21}{2 \times 23-21-14} \times 10 \\ & =\frac{405}{11} \text { or } 36.82 \text { years (approx.) } \end{aligned} \]