Since is a sequence of consecutive integers, and each group of numbers has an odd # of elements:
I * 5 = sum ( G , H , I , J , K)
N * 5 = sum ( L , M , N , O , P)
The sum of five consecutive numbers, divided by 5, will be equal to the value of the median (an also the average), which will match the third value (middle value) of that sequence.
So, being 117 the median of the second sequence of consecutive numbers , multiplying it by the # of elements will bring us to the sum of that 5 numbers.
3 Explanations