SOLUTION: You scored 88.7, 91.2, and 94.6 on your last three test scores. Find the standard deviation of your test scores. A. 0.95 B.1.22 C.2.42 D.4.35

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Question 89006: You scored 88.7, 91.2, and 94.6 on your last three test scores. Find the standard deviation of your test scores.
A. 0.95
B.1.22
C.2.42
D.4.35


Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
First lets find the mean:

To find the mean, add up all of the numbers and divide the sum by the number of numbers (which in this case is 3).


So the mean is 91.5


Use this formula to find the standard deviation:

Standard Deviation: where is the mean, is the ith number, and is the number of numbers



So we can replace N with 3



Replace with 91.5



Expand the summation (replace each with the respective number)




Subtract the terms in the parenthesis



Square each term



Add up all of the terms



Multiply



Take the square root



So the standard deviation is

So if you round to the nearest hundredth, you get 2.42. So the answer is C)
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