UPSC Prelims 2021·CSAT·Quantitative Aptitude·Arithmetic

In a class, 60% of students are from India and 50% of the students are girls. If 30% of the Indian students are girls, then what percentage of foreign students are boys?

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Last updated 8 Jul 2026, 4:39 pm IST
  1. A45%
  2. B40%
  3. C30%
  4. D20%Correct

Explanation

Let's assume the total number of students in the class is 100.

  1. Students from India = 60% of 100 = 60. Students from Foreign = 100 - 60 = 40.

  2. Total number of girls = 50% of 100 = 50. Total number of boys = 100 - 50 = 50.

  3. Girls from India = 30% of Indian students = 30% of 60 = (30/100) * 60 = 18.

Now we can find the number of boys from India and foreign students:

  • Boys from India = Total Indian students - Girls from India = 60 - 18 = 42.
  • Boys from Foreign = Total boys - Boys from India = 50 - 42 = 8.

The question asks for the percentage of foreign students who are boys. Percentage = (Number of foreign boys / Total foreign students) * 100 Percentage = (8 / 40) * 100 = (1/5) * 100 = 20%.

Therefore, 20% of foreign students are boys.

The final answer is D) 20%.

Quantitative Aptitude: In a class, 60% of students are from India and 50% of the students are girls. If 30% of the Indian students are girls, t
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