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In a school, 30 students study both Mathematics and Chemistry. This common group is 10% of all Mathematics enrolments and 12% of all Chemistry enrolments. What is the total number of students who study at least one of these two subjects?

1. 520
2. 490
3. 560
4. 480

Correct answer: 520

Solution

The total number of Mathematics students can be calculated as 30 is 10% of the total, leading to 300 Mathematics students. Similarly, for Chemistry, 30 is 12% of the total, resulting in 250 Chemistry students. Using the principle of inclusion-exclusion, the total number of students studying at least one subject is 300 + 250 - 30, which equals 520.

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