A group of 75 students belonging to three different classes, the following information has been recorded Average mark Deviance fi 

• Class 5A 75 39 04 
• Class 5B 63 24 032
•  Class 5C 55 189

1) How many students belong to class 5C 

2) Does the mark show a larger variability in class 5B or in class 5C 

3) Derive the average mark for the group of 75 students 

4) Derive the TSS for the group of 75 students