For the following data,draw a frequency polygon:

Class	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$	$70-80$
Frequency	$1$	$4$	$5$	$10$	$5$	$4$	$1$

(N/A) To draw a frequency polygon,we first calculate the class marks (mid-values) for each class interval.

Class	Mid-value	Frequency
$10-20$	$15$	$1$
$20-30$	$25$	$4$
$30-40$	$35$	$5$
$40-50$	$45$	$10$
$50-60$	$55$	$5$
$60-70$	$65$	$4$
$70-80$	$75$	$1$

To close the polygon,we include two imaginary classes: $0-10$ with mid-value $5$ and frequency $0$,and $80-90$ with mid-value $85$ and frequency $0$. Plot these points $(5, 0), (15, 1), (25, 4), (35, 5), (45, 10), (55, 5), (65, 4), (75, 1), (85, 0)$ on a graph and join them with line segments.