The weights (in kg) of 10 students of a class are given below :

21, 28.5, 20.5, 24, 25.5, 22, 27.5, 28, 21 and 24. Find the median of their weights.

Arranging the given data in ascending order:

20.5, 21, 21, 22, 24, 24, 25.5, 27.5, 28, 28.5

Here, n = 10, which is even.

By formula,

Median = $\dfrac{\dfrac{n}{2} \text{ th term} + \Big(\dfrac{n}{2} + 1\Big) \text{ th term}}{2}$

$= \dfrac{\dfrac{10}{2} \text{th term} + \Big(\dfrac{10}{2} + 1\Big)\text{ th term}}{2} \\[1em] = \dfrac{5\text{ th term} + 6\text{ th term}}{2} \\[1em] = \dfrac{24 + 24}{2} \\[1em] = \dfrac{48}{2} \\[1em] = 24.$

Hence, median = 24.