A book costs $12.50 plus sales tax. After tax it costs $13.25. What is the sales tax rate?
1 answer:
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<h3>Answer: B) 2.9 approximately</h3>
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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.