The average mark of the students of a class in a particular exam is 80. If 5 students whose average mark in that exam is 60 are excluded, the average mark of the remaining will be 90. Find the number of students who wrote the exam.	Select:
A) 22	B) 27	C) 15	D) 99	E) 21
Let the number of students who wrote the exam be x.   Total marks of students = 80 x.   Total marks of (x - 5) students = 90(x - 5)   80x - (5 * 60) = 90(x - 5)   150 = 10x =&gt; x = 15.Answer: 15
<result>C</result>
The average mark of the students of a class in a particular exam is 80. If 5 students whose average mark in that exam is 60 are excluded, the average mark of the remaining will be 90. Find the number of students who wrote the exam.