Count the Number of Observations ($N$)

Counting the given list of observations: $20, 23, 25, 30, 20, 31, 32, 35, 20, 41, 42, 43, 20, 20, 20$, we find there are $15$ terms in total.

$N = 15$

Arrange Observations in Ascending Order

Sorting the values from smallest to largest: Seven $20$'s, $23, 25, 30, 31, 32, 35, 41, 42, 43$.

$20, 20, 20, 20, 20, 20, 20, 23, 25, 30, 31, 32, 35, 41, 42, 43$

Apply Median Formula for Odd $N$

Since $N = 15$ is odd, the median is the value of the $\left(\frac{N+1}{2}\right)^{\text{th}}$ term.

$\text{Position} = \frac{15+1}{2} = 8^{\text{th}} \text{ term}$

Identify the $8^{\text{th}}$ Term

Looking at the 8th position in the sorted list, the value is $23$.

$\text{Median} = 23$