📚 Study Notes – Average
(For Telangana Patwari / Lekhpal – Quantitative Aptitude)
1. What is an Average?
- Average is a single number that tells us how big or small a set of numbers is on the whole.
- Think of it like a balance scale – it shows the middle point of all the values.
2. How to Find an Average
- Add up all the numbers.
- Count how many numbers there are.
- Divide the total sum by the count.
Formula
[ \text{Average} = \frac{\text{Sum of all numbers}}{\text{Number of numbers}} ]
3. Everyday Analogy
- Example: You have 3 apples that weigh 200 g, 250 g, and 300 g.
- Sum of weights = 200 + 250 + 300 = 750 g
- Number of apples = 3
- Average weight = 750 ÷ 3 = 250 g
- 250 g is the “average” weight of an apple in your set.
4. Quick Tips for Speed
| Situation | Quick Trick |
|---|---|
| Only 2 numbers | Average = (Number 1 + Number 2) ÷ 2. No need to add first. |
| Large numbers | Add them in groups, then divide. |
| Numbers in pairs | Pair the smallest with the largest, add each pair, then average the pair sums. |
5. Tiny Practice Question
A farmer records the number of mangoes harvested each day for 4 days: 120, 150, 130, 140. What is the average number of mangoes harvested per day?
Solution
- Sum = 120 + 150 + 130 + 140 = 540
- Count = 4
- Average = 540 ÷ 4 = 135 mangoes/day.
6. Why It Matters for Patwari / Lekhpal
- Land records: Averaging crop yields, tax amounts, or land sizes helps in fair distribution.
- Data reporting: Quick average calculations make reporting easier and faster.
Quick Recap
- Average = Total ÷ Count
- Use simple addition and division.
- Practice with small numbers first, then speed up with tricks.
Happy studying! 🚀