Question:
In calculating the mean of grouped data, grouped in classes of equal width, we may use the formula,
$\bar{x}=a+\frac{\Sigma f_{i} d_{i}}{\Sigma f_{i}}$
Where, a is the assumed mean, a must be one of the mid-point of the classes. Is the last statement correct? Justify your answer.
Solution:
No, it is not necessary that assumed mean consider as the mid-point of the class interval. It is considered as any value which is easy to simplify it.