Find the number of students who took an exam if the ratio of those who passed to those who failed in the exam was 10 : 3. If 40 more students had taken the exam and 10 less had failed, then the ratio of those who passed to those who failed in the exam would have been 5 : 1.

Find the number of students who took an exam if the ratio of those who passed to those who failed in the exam was 10 : 3. If 40 more students had taken the exam and 10 less had failed, then the ratio of those who passed to those who failed in the exam would have been 5 : 1. Correct Answer 260

Given:

The ratio of passed and failed students = 10 : 3

Calculation:

Let the number of students who took the exam be 13x

So, the number of students who passed = (10/13) × 13x = 10x

Also, the number of students who failed = (3/13) × 13x = 3x

If 40 more students take the exam,

Then total number of students having taken the exam = 13x + 40

If 10 students less fail, then failed students = 3x – 10 

Now, the number of passed students = 13x + 40 – (3x – 10) = 10x + 50

So, the new ratio of passed and failed candidates becomes:

(10x + 50)/(3x – 10) = 5/1

⇒ x = 20

∴ The total number of students who took the exam = 13 × 20 = 260

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