The average marks of 30 students in a class is 60. But a student mark is wrongly noted as 90 instead of 15 then find the correct average marks?	Choose the correct answer:
A) 55.65
B) 57.5
C) 62.5
D) 45.25
E) 50
correct avg marks = 60+(15-90)/30   avg = 60-2.5= 
<gadget id="calculator">60-2.5</gadget>
<output>57.5</output>
57.5   Answer is 57.5
<result>B</result>
The average marks of 30 students in a class is 60. But a student mark is wrongly noted as 90 instead of 15 then find the correct average marks?