If <span la

Given that, …(i)

∑f_iu_i = 20

∑f_i = 100

From the step deviation method, we have the relation of deviation (u_i) and assumed mean (A).

Comparing it with equation (i),

A = 25

h = 10

Using the formula of step deviation method, we have

⇒

⇒ Mean = 25 + 2

⇒ Mean = 27

To find modal class, we need to find frequencies of the data given.

Note the greatest frequency in the data.

So, greatest frequency = 30

Thus, the corresponding class is 30 – 40.

⇒ Modal class = 30 – 40

Thus, mean is 27 and modal class is 30 – 40.