Question

The mean of six numbers is 42. If one number is excluded, the mean of the remaining numbers is 45. Find the excluded number.

Answer 1

The mean of $6$ numbers is $42$.

$\therefore$ Total of $6$ numbers $=6\times 42=252$

The mean of $5$ numbers id $45$.

$\therefore$ Total of $5$ numbers $=5\times 45=225$

$\Rightarrow$ The excluded number $=252-225=27$