The mean of 10 observations is 12. If mean of first 6 observations is 13. Find the mean of remaining 4 observations.

Options

A. 11.5
B. 10.5
C. 12.5
D. 13.5

Answer

B

Explanation

The mean of 10 observations = 12
`therefore "Total sum of 10 observations" = n bar(x) = 12 xx 10 = 120`
The mean of first 6 observations `= 13`
`therefore "Total sum of first 6 observations" = n bar(x) = 13 xx 6 = 78`
Now, total sum of last 4 observations `= 120-78 = 42`
`therefore " The mean of last 4 observations" = (42)/(4) = 10.5`