For the data set 7, 5, 10, 11, 12, the mean, x, is 9. What is the standard
deviation?

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Explanation:

The weird or fancy looking E symbol is the greek uppercase letter sigma. It is effectively the english version of S to represent summation. So we add up all the terms to get this. Luckily this has already been done for us in the table where they wrote "sum = 34", so

From here, we substitute this into the formula, along with n = 5 since there are 5 items in the original list

So,

This computes the sample standard deviation. To get the population standard deviation, you'd basically change the "n-1" to simply "n", and the rest of the formula is identical.

answer: a rhombus has two lines of symmetry that run through one vertex to the one directly across it. unlike a square, planes through the center of each edge of a rhombus do not yield mirrored sides.

step-by-step explanation: