SOLUTION: Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work. Errors Frequency 56-58 22 59-61 14 62-64 24 65-67

Question 452798: Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work.
Errors Frequency
56-58 22
59-61 14
62-64 24
65-67 19
68-70 19

Need to understand the step needed to complete this.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work.
Errors Frequency
56-58 22
59-61 14
62-64 24
65-67 19
68-70 19
Need to understand the step needed to complete this.
-------
You need the class average for each class; called the class mark.
1st class: (58+56)/2 = 57
2nd class: 60
3rd class: 63
4th class: 66
tth class: 69
--------
Multiply each by the frequency for the class
22*57
14*60
24*63
19*66
19*69
----
Add all those products.
Divide by the sum of the frequencies to get the mean.
----
etc.
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Cheers,
Stan H.
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