If mean of 5 observation x, x+2, x+4, x+6 and x+8 is 11, then mean of last three observations is

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If the mean of $5$ observation $x, x+2, x+4, x+6$ and $x+8$ is $11,$ then the mean of the last three observations is

A

$11$

B

$13$

C

$15$

D

$17$

Solution

Mean of 5 observations given.

$\frac{x+x+2+x+4+x+6+x+8}{5}=11$

$x+4=11$

$x=11-4=7$

Mean of last $3$ observations $=\frac{x+4+x+6+x+8}{3}=x+6=7+6=13$

Standard 13

Quantitative Aptitude

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