Regardless of the strategy you used in Problem C4, you must end up with an arrangement in which the sum of the 9 values is equal to 45. Let's look at one possible strategy more closely. Note 6
For the sake of simplicity, we will begin with the line plot that corresponds to the fair allocation, 9 stacks of 5 coins each:
For this line plot, the sum is 45 and the mean is 5.
If we change one of the stacks of 5 coins to a stack of 8, the sum will increase by +3 to 48 and the mean will increase by +3/9 to 5 3/9. The line plot now looks like this: