If xi’s are the mid points of the class intervals of grouped data, fi’s are the corresponding frequencies and is the mean, then is equal to
(A) 0 (B) –1 (C) 1 (D) 2
Solution. Mean: It is the average of the given numbers/observations. It is easy to calculate mean. First of all, add up all the observations and then divide by the total number of observations.
That is mean
By cross multiplication we get
(from equation (1))