Question

If the mean of five observations $x,x+2,x+4$, $x+6$ and $x+8$ is $11$ , then the mean of last three obsevations is-

• A. 11
• B. 13
• C. 15
• D. 17

Answer 1

Answer: (B)

$\because \frac{x+(x+2)+(x+4)+(x+6)+(x+8)}{5}=11$
$\Rightarrow \frac{5x+20}{5}=11$
$\Rightarrow x=7$
$\therefore$ Req. mean $=\frac{11+13+15}{3}=13$