Average score of a class of 60 students, in an exam, was 43. Average score of the students who had passed is 52 and the average score of students who had failed is 16. How many failed the exam?

Answer: Option C

Total number of students in class = 60
Average score of passed student = 52
Average score of failed students = 16
By applying the rule of alligation,

∴ Number of students who failed in exam
= $$\frac{1}{4}$$ × 60
= 15