Question

The average of 5 consecutive numbers is m . If the next three natural numbers are also included, how much more than m will the average of these 8 number he ?

• A. 2
• B. 1
• C. 1.4
• D. 1.5

Answer 1

Answer: (D)

1.5

Let the five consecutive numbers be x, x + 1, x + 2, x + 3, x + 4
Then $\frac{x+x+1+x+2+x+3+x+4}{5}=m$
$\Rightarrow 5x+10=5m\Rightarrow 5x=5(m-2)\Rightarrow x=m-2$
$\therefore$ The 8 consecutive numbers are m - 2, m - 1, m, m + 1, m + 2, m + 3, m + 4, m + 5
Average of these 8 numbers = $\frac{m-2+m-1+m+m+1+m+2+m+3+m+4+m+5}{8}$
= $\frac{8m+12}{8}=m+\frac{3}{2}$
$\therefore$ Required difference = $m+\frac{m}{2}-m=\frac{3}{2}=1.5$