Question 481825: Hi I start then get lost, please help. Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work.
Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work.
Errors Frequency
76-78 12
79-81 25
82-84 6
85-87 25
88-90 10
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
76-78 12
79-81 25
82-84 6
85-87 25
88-90 10
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The class mark represents the class value and
is the average of the class limits.
1st: 77
2nd: 80
3rd: 83
4th: 86
5th: 89
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Multiply each class mark by the class frequency
and add those products
Divide by the total of the frequencies to get the mean = 82.85
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I used a calculator to get the standard deviation = 4.01
The variance is the square of the standev = 4.01^2 = 16.11
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Cheers,
Stan H.
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