UPSC Prelims 2020·CSAT·Quantitative Aptitude·Arithmetic

Consider the following data: | | Average marks in English | Average marks in Hindi | | Girls | 9 | 8 | | Boys | 8 | 7 | | Overall average marks | 8.8 | X | What is the value of x in the above table?

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Last updated 23 May 2026, 3:31 pm IST
  1. A7.8Correct
  2. B7.6
  3. C7.4
  4. D7.2

Explanation

The problem requires us to find the overall average marks in Hindi (X) using the provided data. We can first determine the ratio of the number of girls to the number of boys using the English average marks. 1. **Calculate the ratio of Girls to Boys using English marks:** Let Ng be the number of girls and Nb be the number of boys. Overall average in English = (Average marks of Girls in English * Ng + Average marks of Boys in English * Nb) / (Ng + Nb) 8.8 = (9 * Ng + 8 * Nb) / (Ng + Nb) 8.8 * (Ng + Nb) = 9 * Ng + 8 * Nb 8.8 Ng + 8.8 Nb = 9 Ng + 8 Nb 8.8 Nb - 8 Nb = 9 Ng - 8.8 Ng 0.8 Nb = 0.2 Ng Dividing both sides by 0.2: 4 Nb = Ng This means the number of girls is 4 times the number of boys (Ng : Nb = 4 : 1). 2. **Calculate the overall average in Hindi (X) using this ratio:** Overall average in Hindi (X) = (Average marks of Girls in Hindi * Ng + Average marks of Boys in Hindi * Nb) / (Ng + Nb) Substitute Ng = 4 Nb into the equation: X = (8 * (4 Nb) + 7 * Nb) / (4 Nb + Nb) X = (32 Nb + 7 Nb) / (5 Nb) X = (39 Nb) / (5 Nb) X = 39 / 5 X = 7.8 Therefore, the value of X is 7.8. The final answer is A) 7.8.
Quantitative Aptitude: Consider the following data: | | Average marks in English | Average marks in Hindi | | Girls | 9 | 8 | | Boys | 8 | 7 |

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