# if the mean of 7, 9, 11, 13, x and 21 is 13 find the value of x.

Sum of observations = 7 + 9 + 11 + 13 + 21 +

*x =*61 +

*x*

no. of observations = 6

arithmetic mean = 13

$arithmeticmean=\frac{sumofobservations}{no.ofobservations}\phantom{\rule{0ex}{0ex}}\Rightarrow 13=\frac{61+x}{6}\Rightarrow 61+x=78\Rightarrow x=78-61=17$

Regards

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