<PRE><B>Question 815517</B>
To solve this we know that,
Average of age= total ages of students/ total Students

10 = total ages of students/30

10*30= total ages of students

300= Total ages of students
 
Now
 When 1 student is added there will be total 11 students using above formula

Average of age= Total ages of students/ total ages of students

11 = total ages of students/ 31

Total ages of students= 31*11
                 = 341

Change in total age= 341 - 300
 
Age of 11th student= 41
 Answer= 41</PRE>