Question

6.
Two years ago the mean age of 40 people was 11 years. Now a person left the group
and the mean age has changed to 12 years. Find the age of the person who left the group.
of deviations of all observations of the data 5 8 10​

Answer 1

= Two years ago the mean age for 40 people was 11 years.

∴ Total age of 40 people two years ago =40×11=440

Now, after two years the total age should go up =(2×40)+440=80+440=520.

⇒ When one person left, the for 39 people the mean age is 12.

⇒ Total age of 39 people =39×12=468