The correct option is: b. 3
Explanation
Middle 50% data means the "Interquartile Range" which is measured as the difference between the third quartile[tex](Q_{3})[/tex] and the first quartile[tex](Q_{1})[/tex] in a data set.
In the given box plot, we can see that: [tex]Q_{1}= 4[/tex] and [tex]Q_{3}= 7[/tex]
So, the Interquartile range, [tex]IQR= Q_{3}-Q_{1} = 7-4= 3[/tex]
Thus, the range of the middle 50% of data will be 3.
