The average marks obtained by 150 students in an examination is 40. If the average marks of passed students is 60 and that of the failed students is 20, then what is the number of students who passed the examination?

Let the number of students who passed the examination = $$x$$

=> Number of students who failed = $$(150-x)$$

Average marks of 150 students = 40

=> Total marks = $$40\times150=6000$$

Similarly, total marks scored by passed students = $$60x$$

According to ques,

=> $$60x+20(150-x)=6000$$

=> $$60x+3000-20x=6000$$

=> $$40x=6000-3000=3000$$

=> $$x=\frac{3000}{40}=75$$

$$\therefore$$ The number of students who passed the examination = 75

=> Ans - (C)