Question

Find the mean of the following frequency distribution:
$\begin{array}{cccccc}\text{Variables}\left(x_i\right)& 10& 30& 50& 70& 89\\ \text{Frequency}\left(f_i\right)& 7& 8& 10& 15& 10\end{array}$

Answer 1

Sol:

For calculating the mean, we prepare the following frequency table:

Variable \(Σx_i\)	Frequency \(Σf_i\)	\(Σf_ix_i\)
10	7	70
30	8	240
50	10	500
70	15	1050
89	10	890
	\(Σf_i~=~50\)	\(Σf_ix_i~=~2750\)

Mean = \(\frac{Σf_ix_i}{Σf_i }\) = \(\frac{2750}{50}\) = 55