Let us make the table for above data and containing cumulative frequency and mid-values for each data

MEAN

We know, that

MODE

In the given data,

The maximum class frequency is 30. So, the modal class is 30-40.

Lower limit(l) of modal class = 30

Class size(h) = 40 - 30 = 10

Frequency(f₁) of modal class = 30

Frequency(f₀) of class preceding the modal class = 18

Frequency(f₂) of class succeeding the modal class = 20

And we know,

Substituting values, we get

MEDIAN

In this case,

Sum of all frequencies, n = 100

Now, we know the median class is whose cumulative frequency is greater than and nearest to .

As, Cumulative frequency greater than and nearest to 50 is 63, the median class is 30 - 40.

Median

where l = lower limit of median class,

n = number of observations,

cf = cumulative frequency of class preceding the median class,

f = frequency of median class,

h = class size

In this case,

l = 30

n = 100

cf = 33

f = 30

h = 10

Putting values, we get,

Median