The given data set is 21,31,26,24,28,26.
Arranging the data set in the ascending order,
21,24,26,26,28,31.
The data set contains 6 numbers,
The median can be determined by taking the average of 3rd and 4th term of the data set,
![\begin{gathered} \text{Median}=(26+26)/(2) \\ =26 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/12ang0xq1q8rnsmp11yapvw8z28lhyu5tv.png)
Thus, the required median is 26.
The range can be determined by taking the difference between the highest and the lowest value of the data set,
![\begin{gathered} \text{Range}=31-21 \\ =10 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/hz6gbt7liwvkrcdlw9ennzc8l5us95kuwr.png)
Thus, the range of the data set is 10.
The interquartile range of the data set can be determined by taking the difference of quartile 1 and quartile 3.
![\begin{gathered} \text{IQR}=Q_3-Q_1 \\ =28-24 \\ =4 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/em7d98w19ol19vkrcsjyf0gzlyakxxq1mj.png)
Thus, the required interquartile range is 4.