In an examination, 45% of all the students who appeared are boys and the rest are girls. If 60% of the boys and 70% of the girls passed, then what is the percentage of students who failed?

34.5

Let Total number of students = 100x

Number of Boys = 45% of 100x = 45x

Number of girls = 100x - 45x = 55x

Now,

Passed boys of all the students  = 45x × \(\frac{3}{5}\) = 27x

Passed girls of all the students = 55 ×  \(\frac{3}{5}\) = 38.5x

Students passed in examination = (38.5 + 27)x

= 65.5x

Students failed in examination = (100 - 65.5) = 34.5x

Percentage of failed students = \(\frac{34.5x}{100x}\) × 100 = 34.5 %