the result of the iq test of a group mathematics students in a certain college are presented in a frequency distribution

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the result of the iq test of a group mathematics students in a
certain college are presented in a frequency distribution shown in
the table, Calculate the following:
Mean, Median, Variance, SD, Skewness, Kurtosis, Q3, D4, P25
class interval frequency
70-75
2
76-81
7
82-87
20
88-93
21
94-99
39
100-105
27
106-111
14
112-117
10
118-123
5
n=?