Question

If the mean of observations $x,x+2,x+4,x+6$ and $x+8$ is $11$, find the value of $x$:

• A. $8$
• B. $5$
• C. $6$
• D. $7$

Answer 1

Answer: (D)

$7$

Mean of observations $x,x+2,x+4,x+6,x+8$ is $11$
Mean $=\frac{\text{Sum}}{\text{Number of observation}}$
Mean $=\frac{x+x+2+x+4+x+6+x+8}{5}=11$
$\frac{5x+20}{5}=11$
$5x+20=55$

$5x=55-20$

$5x=35$
$x=7$

Hence the answer is option $D$