Question

If the mean of five observations x,x+4,x+8,x+12 and x+16 is 15,then find the mean of the observations.

Answer 1

You mean find the observations because the mean is already given as 15.

So to find the observations
(x + x+4 + x+8 + x+12 + x+16) / 5 = 15

5x + 40 = 15

5x = 15-40

5x = -25

x = -25 / 5

x = -5

Now here the observations will be :

x = -5

x+4 = -5+4 = -1

x+8 = -5+8 = 3

x+12 = -5+12 = 7

x+16 = -5+16 = 11

Therefore the observations are
-5 , -1 , 3 , 7 , 11

Now just to check the answer

Mean of the observations is
(-5 + -1 + 3 + 7 + 11) / 5

= -6+10+11

= 15

Hence, verified also.









HOPE IT HELPS : )