Question

the mean of first 8 observation is 18 & last 8observation is 20 . if thevmean of all 15 observation is 19 find the 8th observation

Answer 1

the 8th observation is 19
Hope it's helpful

Answer 2

The mean of first 8 observation
18=sum of all number/8
18×8=x
144=x

The mean of last 8 observation
20 = x/8
20×8=x
160=x

The mean of all 16 no. = 160+144
= 304
The mean of 15 no. = 19=x/15
=285
The 1 no. left =304-285
= 19