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**BabyMilo** The times $\displaystyle x_{1},x_{2},x_{3},...,x_{20}$, in minutes, taken by 20 employees to complete a task are summaried by

$\displaystyle \sum(x-50)=140$

using $\displaystyle \overline{x}=\frac{\sum x}{n}$

$\displaystyle \overline{x}=\frac{140}{20}=7$

then add 50 to 7 = 57 is the $\displaystyle \overline{x}$

but in the back of the book, it says 52.8.

Which one is right?

for the 52.8, it uses $\displaystyle \overline{x}=\frac{140}{50}=2.8$

then add 50.

again, Which one is right?

thanks for your help!