Find the mean and variance for the data
x_i  6  10  14  18  24  28  30 
f_i   2    4    7   12   8    4    3

Solution:

Let us draw the table based on the given information

Here, N = 40 and ∑⁷_{i = 1} f_ix_i = 760

Therefore,Mean can be calculated as:

 x = 1/N ∑⁵_{i = 1} f_ix_i

= 760 / 40

= 19

Variance,

(σ²) = 1/n ∑¹⁰_{i = 1}(x_i - x)²

= 1/40 x 1736

= 43.4

NCERT Solutions Class 11 Maths Chapter 15 Exercise 15.2 Question 4

Find the mean and variance for the data xi  6  10  14  18  24  28  30  fi   2    4    7   12   8    4    3

Summary:

The mean and variance for the given data are 19 and 43.4