The average of five consecutive natural numbers is m. If the next three natural numbers are also included, how much more than m will the average of these 8 numbers be ?
Let the five consecutive natural numbers be a, b, x, d, e where a = x - 2, b = x - 1, x = x, d = x + 1 and e = x + 2.
That's like (x - 2), (x - 1), x, (x + 1), (x + 2). The average of those natural numbers is (x−2)+(x−1)+x+(x+1)+(x+2)5 (to find the average you must add the n natural numbers together and divide by the total number of the consecutive numbers m).
(x−2)+(x−1)+x+(x+1)+(x+2)5=5x5=m, this brings us to m = x. The next three natural numbers are f, g, h where f = x + 3, g = x + 4, h = x + 5, or better to say x + 3, x + 4, x + 5.
(x−2)+(x−1)+x+(x+1)+(x+2)+(x+3)+(x+4)+(x+5)8 -
Now shorten the - 2 and 2, -1 and 1 ⇒x+x+x+x+x+(x+3)+(x+4)+(x+5)8=8x+(3+4+5)8=8x+128=x+128.
We know that m = x, so x+128=m+1.5.
Therefore, the average of the 8 consecutive natural numbers is 1.5 more than m.