###
**If the mean of 5 observations x, x + 2, x + 4, x + 6 and x + 8 is 11, then the mean of the last three observations is-
**

A. 11
B. 13
C. 15
D. 17
**Answer: Option B**

## Show Answer

Solution(By Apex Team)

$\begin{aligned}&\text{We have;}\\
&\Rightarrow\frac{x+(x+2)+(x+4)+(x+6)+(x+8)}{4}=11\\
&\Rightarrow5x+20=55\\
&\Rightarrow x=7\\
&\text{So, the numbers are 7, 9, 11, 13, 15}\\
&\text{∴ Required mean}\\
&=\left(\frac{11+13+15}{3}\right)\\
&=\frac{39}{3}\\
&=13\end{aligned}$

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