Question

Calculate the mean from the following data :

$\begin{array}{cccccc}\text{C.I}& 10-20& 10-30& 10-40& 10-50& 10-60\\ \text{f}& 5& 17& 31& 41& 49\end{array}$

Answer 1

The given data is in cumulative frequency form. Firstly, it is converted into simple frequency form.

$\overline{X}=A+\frac{\sum f{d}^{{}^{\prime }}}{N}\times i=35+\frac{4}{49}\times 10=35.8$