Explanation:

Correct option 3: 616

Given : 55% of the candidates in an examination were boys 60% of the boys and 75% of the girls passed 315 girls failed

Solution: 

Let total number of candidates in the exam be 100N.

Number of boys in the exam = 55N

Number of girls = 45N

Now, According to the question, 75% of the girls passed hence 25% of girls failed.

So, 45N x 1/4 = 315

45N = 1260

N = 28

So, 55N = 28 x 55 Now, boys who failed = 28 x 55 x 2/5

28 x 22 = 616 :. The number of boys who failed were 616