The percentage of marks obtained by 100 students in an examination are given below: Determine the median percentage of marks.

Class	$\displaystyle f$	$\displaystyle c f$
$\displaystyle 30$-$\displaystyle 35$	$\displaystyle 16$	$\displaystyle 16$
$\displaystyle 35$-$\displaystyle 40$	$\displaystyle 14$	$\displaystyle 30$
$\displaystyle 40$-$\displaystyle 45$	$\displaystyle 18$	$\displaystyle 48$
$\displaystyle 45$-$\displaystyle 50$	$\displaystyle 20$	$\displaystyle 68$
$\displaystyle 50$-$\displaystyle 55$	$\displaystyle 18$	$\displaystyle 86$
$\displaystyle 55$-$\displaystyle 60$	$\displaystyle 12$	$\displaystyle 98$
$\displaystyle 60$-$\displaystyle 65$	$\displaystyle 2$	$\displaystyle 100=N$

Median class is $\displaystyle 45$-$\displaystyle 50$ \[\begin{aligned} \text { Median } & =45+\frac{5}{20}(50-48) \\ & =45 \cdot 5 \end{aligned} \]Therefore, Median percentage of marks is $\displaystyle 45.5$