If the mean of 5 observations x, x + 2, x + 4, x + 6 and x + 8 is 11, find the value of x.

Mean of the observation is given by –

So, adding the given observations, we get

Sum of the given observations = x + (x + 2) + (x + 4) + (x + 6) + (x + 8)

= x + x + 2 + x + 4 + x + 6 + x + 8

= 5x + 20

Total number of observations = 5

Mean = 11 (Given)

⇒

⇒ 55 = 5x + 20

⇒ 5x = 55 – 20 = 35

⇒ x = 7

Thus, x = 7