Total number of students = 480
Percentage of total students passed
= 75 % of total student = \( \Large \frac{75 \times 480}{100} = 360 students\)
Now, using the condition from the question,
Let the number of boys be x
Then, 70% of x + 85% of (480 - x) = 360
=> \( \Large \frac{70 \times x}{100} + \frac{85 \times (480 - x)}{100} = 360 \)
=> 70x - 85x + 40800 = 36000
=> 40800 - 36000 = 85x - 70x
=> 4800 = 15x
=> \( \Large x = \frac{4800}{15} = 320 \)
There are 320 boys who have appeared for the examination.