Statistics Sequences Series

If the mean deviation of the numbers 1, 1 + d, 1 + 2d, ... , 1 + 100d from their mean is 255, then the d is equal to

  1. 10
  2. 10.1
  3. 20
  4. 20.2

Answer

| (x - mean)/n | =  255

Mean = (1 + 1 + 2d + 1 + 3d + ... +1+ 100d)/101

= 101 + d(100x101/2)/101

= 1 + (50x101d)/101

= 1+ 50d

|x - mean| = 255 x 101

The correct option is B.