Try the following GMAT Problem Solving question on statistics that requires being able to find the sum and average of a set of numbers when the values in the list are changed.
Question 64:
A set of $n$ numbers has the sum $s$. Each number of the set is increased by $20$, then multiplied by $5$, and then decreased by $20$. The sum of the numbers in the new set thus obtained is:
-
$\quad s+20n$
-
$\quad 5s+80n$
-
$\quad s$
-
$\quad 5s$
-
$\quad 5s+4n$