SOLUTION: The test scores of 40 students are summarized in the frequency table below. Find the standard deviation. Score Students 50-59 12 60-69 8 70-79 10 80-89 5 90-99 5 Ive never

Question 233454: The test scores of 40 students are summarized in the frequency table below. Find the standard deviation.
Score Students
50-59 12
60-69 8
70-79 10
80-89 5
90-99 5
Ive never done standard deviation on numbers that are ranged, so I dont even know how to set up the problem.

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The test scores of 40 students are summarized in the frequency table below. Find the standard deviation.
Score Students
50-59 12
60-69 8
70-79 10
80-89 5
90-99 5
Ive never done standard deviation on numbers that are ranged, so I dont even know how to set up the problem.
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You use the class mark as the representative value for each class.
The class mark for the 1st class is (59+50)/2 = 109/2 = 54.4
And the frequency of that value is 12.
---------------
Do the same for each class. Then determine the std.
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Cheers,
Stan H.
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