Step 1: Set up a cumulative frequency distribution table

NOTE: The cumulative frequency is calculated using a frequency

distribution table.

Step 2: Calculate the median class of the data.

NOTE: Locate the class whose cumulative frequency exceeds \frac{n}{2} for the first time. This is called the median class.

The total number of observations n = 30

\frac{n}{2}=\frac{30}{2} = 15

55 - 60 is the class whose cumulative frequency is 6 greater than (and nearest to) \frac{n}{2}, i.e.,15

Therefore, 55 - 60 is the median class

Step 3: Substitute that values in the median formula

From the table;

l = lower boundary of median class = 55,

n = number of observations = 30,

cf = cumulative frequency of class preceding the median class = 13

f = frequency of median class = 6

h = class size (size of the median class) = 60 - 55 =.5

Substituting the values

Median = l + \frac{\frac{n}{2}-cf}{f}*h

Median = 55 + \frac{15 - 13}{6}*5

= 55 + \frac{5}{3}

Hence, the median = 56.67