🎙 Teacher-Style Introduction

Average chapter बहुत scoring और आसान होता है। Delhi Police exam में हर साल 1–2 direct सवाल आते हैं — बस total निकालो और संख्या से divide कर दो।

📘 Important Formulas

• Average = (Sum of items) / (Number of items)
• Total = Average × Number
• New Average Method (जल्दी हल करने का तरीका)
• Equal increase/decrease → average भी उतना ही बदलता है

⚡ Tricks

• “Equal change method” सबसे तेज़
• Missing number निकालने का fastest तरीका → Total difference method

✔ Examples

Example 1: Numbers: 4, 6, 8 Average = (4+6+8)/3 = 6

Example 2: Avg = 20, items = 6 → Total = 120

Example 3: Five numbers avg = 10. If sixth is 20 → New avg?
Total old=50, new total = 70 → avg = 70/6 = 11.67

Example 4: Avg of 5 numbers is 18. One number is 28.
Remaining total = 90−28 = 62 → avg = 15.5

Example 5: If a number 10 is removed from avg 15 of 6 numbers:
Total old=90, new total=80 → new avg=80/5= 16

✔ MCQs

1. Avg of 10 & 20 → 15
2. Avg=12 for 5 numbers → total= 60
3. Numbers: 3,5,7 → avg= 5
4. Avg of 4 nos = 8 → total = 32
5. Avg=20 for 4 nos, sum of 3 nos=50 → 4th = 30
6. Avg increases from 10 to 11 → increase = 1
7. Avg=25 for 8 → total= 200
8. Removing 20 reduces avg by 2 → count? 10
9. Avg=14 for 7 nos → total = 98
10. Avg=30 for 3 nos, 4th=18 → new avg = 27

🔥 Challenge

Avg of 6 numbers is 15. Seventh is 27. New avg?

Old total = 90 New total = 117 New avg = 117/7 = 16.71