Question

In a class, 60% of the students are girls and the rest are boys. There are 30 more girls than boys. If 68% of the students, including 30 boys, pass an examination, the percentage of the girls who do not pass is

• A. 10
• B. 20
• C. 30
• D. 25

Answer 1

Answer: (B)

20

Answer 2

Let the number of girls be represented by 3x and the number of boys by 2x.
Given that 3x - 2x = 30, solving for x yields x = 30. Thus, the total number of students is 3x + 2x = 5x, which equals 150.
The number of girls (3x) and boys (2x) is 90 and 60, respectively.
The number of students who pass the exam is 68% of 150, which is 102.
Out of these, the number of girls who pass the exam is 102 - 30 = 72.
Consequently, the number of girls who fail the exam is 90 - 72 = 18.
Therefore, the percentage of girls failing the exam is $\frac{18}{90}\times100$ = 20%