The average of marks obtained by 100 candidates in a certain examination is 30. If the average marks of passed candidates is 35 and that of the failed candidates is 10, what is the number of candidates who passed the examinations ?

Answer: Option C

Solution

Answer: Option C

Solution:

By mixture and allegation method.

4 : 1 = 5 units
5 units = 100
1 unit = 20
Pass candidate :
= 4 units
= 4 × 20
= 80