Question

If the mean of 5observation is x,x+2,x+4,x+6,x+8 is 11.find the mean of first 3 observations

Answer 1

(x + x + 2 + x + 4 + x + 6 + x + 8) / 5 = 11
x + x + 2 + x + 4 + x + 6 + x + 8 = 55
5x + 20 = 55
5x = 35
x = 7
Now, substitute for x in each of the last three terms:
x + 4 + x + 6 + x + 8 = (7 + 4) + (7 + 6) + (7 + 8) = (11) + (13) + (15) = 39 / 3 = 13
The mean is 13.