Solution

The middle value in a sorted, ascending or descending list of numbers is known as the median. This is why the median is termed as a positional average of the data set because it divides the whole data set into two equal parts, containing an equal number of elements. Quartiles are values from the dataset which divide the whole data sets into four equal parts. The first quartile value or Q1 has 25% elements of the data set below it. Likewise, Q2 has 50% elements below it and it divides the data set into exactly two equal parts. Decile divides a data set into 10 equal parts, segregated by 9 positional elements, named D1, D2, ..., and D9. Out of these 9 values, D5 is the middlemost value which divides the whole dataset into two equal parts. Hence the correct answer is option D.