Question

In a certain exam, the ratio of the number of students passed to the number of students failed is 7: 4. Has 8 more students passed, the ratio of the number of students passed to the number of students failed would have been 9: 2. Find the number of students who failed in the exam.
A) 20
B) 16
C) 12
D) 24
E) None of these

Answer 1

Please see the attachment

Answer 2

The number of students who failed in the exam is 16

Solution:

Ratio of the number of students passed to the number of students failed is 7: 4

Let the number of students passed = 7x

Let the number of students failed = 4x

Total = 7x + 4x = 11x

Thus,

Total students appeared = 11x

Has 8 more students passed, the ratio of the number of students passed to the number of students failed would have been 9: 2

Therefore,

7x + 8 : 4x  - 8 = 9 : 2

Then,

$\frac{7x+8}{4x-8} = \frac{9}{2} \\\\14x + 16 = 36x - 72\\\\22x = 88\\\\ x = 4$

Find the number of students who failed in the exam

number of students failed = 4x

number of students failed = 4(4) = 16

Thus number of students who failed in the exam is 16

Learn more:

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