A set of eight numbers has mean 5 and SD 4. The number 21 and another integer n are added to the set. The standard deviation of the set is now 6. Find n and the mean of the set now.
Set of numbers given, find mean and SD of the other
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statistics
standard-deviation
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0Finding the sum and the sums of squares, trying to form equations about variance. – 2012-02-27
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0I fooled around some and using SD equal to the square root of $(1/8)\sum(x_i-\bar{x})^2$, got an equation that seems not to give integer $n$. But it was done quickly and I am accident-prone. – 2012-02-27