SSC Selection Post 2020 PYQ — Question 72

The correct answer is option 3 i.e. k + 4.

 

The five consecutive even numbers be:

x , x + 2 , x+4 , x+6 , x+8

Average  = $\frac{x + (x + 2) + (x + 4) + (x + 6) + (x + 8)}{5} = \frac{5x + 20}{5} = x + 4$

$x + 4 = k \implies x = k - 4$

Next four consecutive even numbers =  x+10 , x+12 , x+14 , x+16

Sum of first five numbers:

$S_1 = 5 \times k = 5k$

Sum of next four numbers:

$S_2 = (x + 10) + (x + 12) + (x + 14) + (x + 16) = 4x + 52$

x = k - 4

$S_2 = 4(k - 4) + 52 = 4k - 16 + 52 = 4k + 36$

Total sum of all nine numbers:

$S = S_1 + S_2 = 5k + 4k + 36 = 9k + 36$

Average = $\frac{9k + 36}{9} = k + 4$