Q. 9 A5.0( 7 Votes )

# Let us find the mean of the following data by step deviation method.

Answer :

To find mean using step-deviation method, we need to create a table showing frequencies, midpoints and deviations.

Observe that class size, h = (30 – 0) = (60 – 30) = … = (150 – 120) = 30

We have,

A = 75

∑f_{i}u_{i} = 2

∑f_{i} = 80

h = 30

By step deviation method, we can give the formula of mean as:

Using the above values, we have

⇒

⇒

⇒

*⇒*

*⇒* *Mean = 75.75*

**Thus, mean is 75.75.**

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