Find the mean deviation about the mean for the data
x_i  5  10  15  20  25
f_i   7    4    6    3    5

Solution:

Let us make the table of given data

N = ⁵∑_{i = 1} f_i = 25 and ⁵∑_{i = 1} f_ix_i = 350

Therefore,

x = 1/N ⁵∑_{i = 1} f_ix_i

= (1/25) × 350

= 14

Mean deviation about the mean

M.D. (x) = ⁸∑_{i = 1} (|x_i - x|)/8

= 1/25 × 158

= 6.32

NCERT Solutions Class 11 Maths Chapter 15 Exercise 15.1 Question 5

Find the mean deviation about the mean for the data xi  5  10  15  20  25  fi   7    4    6    3    5

Summary:

The mean deviation about the mean for the given data is 6.32