a sixth number will be added to the list. what must it be in order for the mean to be 12To find the number that must be added to the list in order for the mean to be 12, we need to know the sum of the first five numbers in the list. Once we have that, we can subtract that sum from the product of 12 and 6 (since there will be six numbers in total) to find the number that should be added to the list.