Hi! I think I understand the question.
The error in the plot is the median and the lower quartile.
From smallest to largest, these are the numbers with the median, lower quartile, and upper quartile are pointed out:
3,3,4| 4.5 |4,5,5| 5.5 |6,7,7| 7.5 |8,8,9
As you can see above, the correct median and lower quartile are 5.5 and 4.5. In your plot, the median and lower quartile are 6 and 4.
I hope this helped and I hope you're feeling better. :)
