Use the histogram to complete the table below

The x-axis shows the class boundaries.
The class width is the difference between the upper and lower class boundaries.

Frequency density is given by the height of each bar.

Frequency = Frequency density $\times$ Class width.

Midpoint = (Lower class boundary + Upper class boundary) / 2.

The completed table is:

Total frequency $N = 4 + 6 + 22 + 26 + 6 + 2 = 66$.
Median position = $\frac{N}{2} = \frac{66}{2} = 33^{rd}$ value.

We need to find the class where the $33^{rd}$ value lies.
Cumulative frequencies:
19.5-29.5: 4
29.5-34.5: $4+6=10$
34.5-54.5: $10+22=32$
54.5-74.5: $32+26=58$
The $33^{rd}$ value falls into the class $54.5 - 74.5$. This is the median class.

The median formula is:

Where:
$L$ = Lower class boundary of the median class = 54.5
$N$ = Total frequency = 66
$CF_b$ = Cumulative frequency of the class before the median class = 32
$f_m$ = Frequency of the median class = 26
$c$ = Class width of the median class = $74.5 - 54.5 = 20$

Substitute the values into the formula:

Rounding to two decimal places:
The median is $\boxed{55.27}$.