Question

The sum of deviation of a certain number of items measured from 2.5 is 50 and from 5.5 is - 250.Find the arthmetic mean

Answer = 3100​

Answer 1

3

Explanation:

Given that :

A1 = 2.5 ; Σdx1 = 50

A2 = 5.5 ; Σdx2 = -250

Mean (m) = A + Σdx/N = 50

m = A + Σdx/N

m - A = Σdx/N

Nm - NA = Σdx

From the parameters given :

Nm - 2.5N = 50 - - - (1)

Nm - 5.5N = - 250 - - - (2)

Subtract (1) from (2)

3N = 300

N = 300/3

N = 100

Put N = 100 in either (1) or (2)

From (2):

100(m) - 5.5(100) = - 250

100m - 550 = - 250

100m = - 250 + 550

100m = 300

m = 300/100

m = 3

Hence, Arithmetic mean = 3