Draw a frequency polygon for the following frequency distribution:

Class	$0-10$	$10-20$	$20-30$	$30-40$	$40-50$
Frequency	$6$	$4$	$10$	$12$	$5$

(N/A) To draw a frequency polygon, follow these steps:
$1$. Calculate the class marks (mid-points) for each class interval using the formula: $\text{Class mark} = \frac{\text{Lower limit} + \text{Upper limit}}{2}$.
- For $0-10$: $\frac{0+10}{2} = 5$
- For $10-20$: $\frac{10+20}{2} = 15$
- For $20-30$: $\frac{20+30}{2} = 25$
- For $30-40$: $\frac{30+40}{2} = 35$
- For $40-50$: $\frac{40+50}{2} = 45$
$2$. Create a table of (class mark, frequency) coordinates: $(5, 6), (15, 4), (25, 10), (35, 12), (45, 5)$.
$3$. To close the polygon, include two additional classes with frequency $0$: one before the first class $(-10-0)$ with class mark $-5$ and one after the last class $(50-60)$ with class mark $55$.
$4$. Plot these points on a graph paper where the $x$-axis represents the class marks and the $y$-axis represents the frequencies.
$5$. Join the points with straight line segments to form the frequency polygon.