Question

if a,b,c,d,e are five consecutive odd numbers, their average is?

Answer 1

when there are numbers which differ by the same number like 2 in the given data, the average is found easily.

Average = sum / 5
           = [2n+1 + 2n+3 + 2n +5 + 2n+7 + 2n+9 ]/5 = 2n+5 = c

=======================   simple quick method:

average of a and e = the middle number  c.
average of b and d = also c.
average of c =  c itself.

Thus average of all numbers = c.