Question

The mean of six numbers is $23$. If one of the numbers is excluded, the mean of the remaining numbers is $20$. Find the excluded number.

Answer 1

Mean of six number$=23$
Total of six number$23\times 6$
$=138$
Let number excluded$=x$
Total$=138-x$
Mean of $5$ number$=\frac{138-x}{5}=20$
$138-x=100$
$x=38$

the excluded number is $38$