The Average marks in statistics of 10 students were 68. A new student with 72 marks where as 2 existing students left the college. If the marks of these students were 40 39, find the Average marks?

average=total marks/total students

68=total marks/10

68*10=total marks

680=total marks

now adding the marks of new student and subtracting the marks of students who left we will get new total marks i.e,

680+72-40-39=673

and adding new student to total students and subtracting 2 students who left from them we get new no. of students

10+1-2

now, new average=new total marks/new no. of students

new average=673/9

new average=74.78