SSC CGL 30 Aug 2015 Paper

Question : 139 of 200

Marks: +1, -0

The average of 6 consecutive natural numbers is K. If the next two natural numbers are also included, how much more than K will the average of these 8 numbers be?

Validate

Solution:

x + x + 1 + x + 2 + x + 3 + x + 4 + x + 5 = 6K
⇒ 6x + 15 = 6K
⇒ x +

{1}/6

= K
⇒ x +

5/2

= K ... (i)
Again,

{x+(x+1)+....(x+6)+(x+7)}/8

{8x}/8 + {28}/8

= x +

7/2

... (ii)
Now , x +

7/2

- x -

5/2

= 1

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