Q. Consider the following data:
Girls’s Average marks in English = 9
Girls’s Average marks in Hindi = 8
Boys’s Average marks in English = 8
Boys’s Average marks in Hindi = 7
Overall Average marks in English = 8.8
What is the value of Overall Average marks in Hindi?
(a) 7.8
(b) 7.6
(c) 7.4
(d) 7.2
Correct Answer: (a) 7.8
Question from UPSC Prelims 2020 CSAT Paper
Explanation :
Overall Average marks in Hindi
Let’s solve this step by step:
1. Given:
x = number of girls
y = number of boys
2. English marks equation:
Total marks = (9x + 8y)
Average = 8.8
Therefore: (9x + 8y)/(x + y) = 8.8 … (1)
3. Hindi marks:
Total marks = (8x + 7y)
From equation (1), we found: x = 4y
4. Substituting x = 4y in Hindi marks:
Total marks = 8(4y) + 7y
= 32y + 7y
= 39y
5. Final calculation:
Average Hindi marks = 39y/(5y)
= 7.8
Therefore, the overall average marks in Hindi is 7.8.