📊 Quantitative Aptitude – Average
Goal: Know what an average is, how to find it, and why it matters.
1️⃣ What Is an Average?
- Average = “typical value” of a set of numbers.
- Think of it as the balance point of all the numbers.
- Everyday example: the average of your test scores gives a single number that represents how you did overall.
2️⃣ Quick Analogy
- Imagine a scale with a bunch of balls on it.
- The average is the point on the scale where it balances evenly.
- If the balls are of equal weight, the balance point is simply the middle ball’s weight.
3️⃣ Formula (Very Simple)
Average = (Sum of all numbers) ÷ (Count of numbers)
- Sum = add them all up.
- Count = how many numbers you added.
4️⃣ Step‑by‑Step Example
You have four numbers: 10, 20, 30, 40.
| Step | Action | Result |
|---|---|---|
| 1 | Add them: 10 + 20 + 30 + 40 | 100 |
| 2 | Count them: 4 numbers | 4 |
| 3 | Divide: 100 ÷ 4 | 25 |
Average = 25
5️⃣ Quick Tips
| Tip | Why it Helps |
|---|---|
| Use a calculator | Saves time and avoids mistakes. |
| Check the count | A wrong count changes the answer. |
| Round only at the end | Keeps the calculation exact. |
6️⃣ Common Mistakes
| Mistake | Fix |
|---|---|
| Adding the wrong numbers | Double‑check the list first. |
| Dividing by the wrong count | Write the count down next to the sum. |
| Rounding early | Round only the final result. |
7️⃣ Practice Problems
- Numbers: 5, 15, 25, 35.
- Numbers: 12, 18, 24, 30, 36.
- Numbers: 7, 14, 21, 28, 35, 42.
(Use the formula above.)
8️⃣ Answers
| Problem | Sum | Count | Average |
|---|---|---|---|
| 1 | 70 | 4 | 17.5 |
| 2 | 120 | 5 | 24 |
| 3 | 147 | 6 | 24.5 |
9️⃣ Summary
- Average gives a single number that represents a group.
- Formula: add all numbers → divide by how many.
- Practice with small sets first; it builds confidence.
- In networking exams, averages often appear in data analysis and performance questions—know this and you’ll be ready!