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?
Answer & explanation
Answer: (a) 7.8
The overall English average of 8·8 lies four times nearer the girls' 9 than the boys' 8, so girls outnumber boys 4 : 1. Using the same weights on Hindi gives (4 × 8 + 1 × 7)/5 = 7·8.
- Let there be g girls and b boys. English: 9g + 8b = 8·8(g + b).
- So 0·2g = 0·8b, giving g : b = 4 : 1.
- Hindi: x = (4 × 8 + 1 × 7)/5 = 39/5 = 7·8.
- Check: English with the same weights = (4 × 9 + 8)/5 = 44/5 = 8·8.
Remember · Use the known overall average to find the group ratio, then apply that ratio to the other subject.
Question and answer: UPSC's official GS Paper II (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). ·