Question

In a data, the mean of first 8 observation is 18, and last 8 observations are 20 if the mean of all 15 observations in 19. Find the value of 8 observation

Answer 1

The value of 8th observation is 19.
Explanation:

Mean of all 15 observation is 19.
Total value is: 15 x 19 = 285

Mean of first 8 observation is 18.
Total value of first 8 observations is: 8 x 18 = 144

Mean of last 8 observation is 20.
Total value of last 8 observations is: 8 x 20 = 160

So the 8th observation is: (total value of first 8 observation + Total value of last 8 observations) - Mean of all 15 observation is 19
=(144+160)-285= 304-285= 19
Hence, the 8th observation is 19.

Answer 2

Please see the attachment