In an examination, out of 480 students, 85% of girls and 70% of boys pass. How many boys appeared for the examination, if the total pass percentage of the examination is 75%?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 320
Step 1: Let the number of boys and girls
Let the number of boys = B
Then the number of girls = 480 − B
Step 2: Number of students who passed
- 85% of girls pass → $0.85(480 - B)$
- 70% of boys pass → $0.70 B$
Total students passed = 75% of 480 →
$0.75 \times 480 = 360$
Step 3: Form the equation
$0.85(480 - B) + 0.70 B = 360$
$408 - 0.85B + 0.70B = 360$
$408 - 0.15B = 360$
$0.15B = 408 - 360 = 48$
$B = \frac{48}{0.15} = 320$