Find the mean of the
set of numbers:
15, 13, 12, 12, 20

Add all the numbers together and divide them by the number of numbers you added to get the mean (in other words the average)

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)