This problem will take you through calculating the mean for grouped data by hand.

The reason that the class midpoint is used in the table below is because it is the expected value for the average score in each class.

Part A:

Lower Class Limit Upper Class Limit Frequency Class midpoint Frequency times midpoint
60 64 11    
65 69 19    
70 74 15    
75 79 10 77 770
65 69 8 67 536
85 89 6 87 522
90 94 3 92 276
95 99 1 97 97
100 104 1 102 102

Part B: Now add up the last column of the table above.  

Part C: Now add up the third column of your table.  

Part D: Now divide your answer to Part B by your answer to Part C. This is the mean for the Grouped Frequency Data Table (GFDT).   

 

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