There's no 50 in the question but you have used 50 as the maximum instead of 51

The given data points are: 9, 21, 49, 10, 40, 51, 28, 37, 18, 21, 22, 8, 30, 34, 12, 45, 43, 9, 31, 12.
Rearranging the data in ascending order:

$$8, 9, 9, 10, 12, 12, 18, 21, 21, 22, 28, 30, 31, 34, 37, 40, 43, 45, 49, 51$$

The number of data points is $n = 20$.

The range is the difference between the maximum and minimum values in the dataset.
Maximum value = 51
Minimum value = 8

$$\text{Range} = \text{Maximum value} - \text{Minimum value} = 51 - 8 = \boxed{\text{43}}$$

The calculations for Q1, Q3, IQR, and SIQR remain the same as they do not depend on the maximum value being 51 instead of 50 in this specific dataset.

• Lower Quartile (Q1): $\boxed{\text{12}}$
• Upper Quartile (Q3): $\boxed{\text{39.25}}$
• Interquartile Range (IQR): $\boxed{\text{27.25}}$
• Semi-Interquartile Range (SIQR): $\boxed{\text{13.625}}$