Answer variants:
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Determine the value of "\(a\)" if the mean of the following data is 20.
 
Class interval\(5 - 10\)\(10 - 15\)\(15 - 20\)\(20 - 25\)\(25 - 30\)\(30 - 35\)
Frequency994\(a\)21
 
The value of the variable is
.