Question

If ui= (xi - 25 )/10, Σfiui =20, Σfi =100, then x =
(a)23
(b)24
(c)27
(d)25

Answer 1

SOLUTION :  

The correct option is (c) : 27

Given : ui = (xi - 25)/10 , Σfiui = 20 , Σfi= 100

ui = (xi - A)/h  = (xi - 25)/10

Therefore , h = 10 , A = 25

MEAN(x) = A + h ×(Σfiui /Σfi)  

= 25 + 10 (20/100)

= 25 + 2

= 27  

x = 27

Hence, the Mean(x) is 27 .

STEP DEVIATION METHOD:

Step deviation method is used in the cases where the deviation from the assumed mean 'A' are multiples of a common number. If the values of ‘di’ for each class is a multiple of ‘h’ the calculation become simpler by taking ui= di/h = (xi - A )/h

Here, h is the class size of each class interval

HOPE THIS ANSWER WILL HELP YOU….

Answer 2

The correct answer is c. 27