9 क्रमागत संख्याओ का औसत n है । यदि अगली 2 संख्याओ को भी सम्मीलीत किया जाये तो नया औसत ज्ञात करे?

Options

A. increase by 2
B. remain the same
C. increase by 1.5
D. increase by 1

Answer

D

Explanation

let the number are `=x,x+1, x+2,x+3,x+4,x+5,x+6,x+7,x+8`
According to question
`(x,x+1, x+2,x+3,x+4,x+5,x+6,x+7,x+8)/9`
`(9x+36)9=n`
x+4=n
If next two number also include (x+9,x+10) then average `=(9x+36+x+9+x+10)/11`
`=(11x+55)/11`
average = x+5
Difference = x+5-x-4
Difference =1 (Increase by 1)