If for some `x in R` the frequency distribution of the marks obtained by 20 statement in a test is :
Channel: Doubtnut
Date: 2020-07-12

If for some `x in R` the frequency distribution of the marks obtained by 20 statement in a test is :  `{:("Marks",2,3,5,7),("Frequency",(x + 1^(2)),(2x - 5),(x^(2) - 3x),x):}` then the mean of the marks is :