Percentages — Lesson
1) Hook — A Fun Real-Life Story to Grab Attention
Imagine you are at a cricket match watching your favourite player, Virat Kohli. The stadium is packed with 50,000 fans. Suddenly, the announcer says, "Today, 20% of the crowd are wearing blue jerseys supporting Team India!" You wonder, how many people is that exactly? This is where percentages help us turn such statements into real numbers!
2) Core Concepts — What Are Percentages?
A percentage is a way to express a number as a part of 100. The word percent means per hundred. So, 20% means 20 out of 100.
We write percentages using the % symbol. Here are some examples:
| Percentage | Fraction | Decimal | Example |
|---|---|---|---|
| 25% | 25/100 = 1/4 | 0.25 | 25% of 200 = 50 |
| 50% | 50/100 = 1/2 | 0.5 | 50% of 80 = 40 |
| 10% | 10/100 = 1/10 | 0.1 | 10% of 500 = 50 |
How to calculate a percentage of a number?
- Step 1: Convert the percentage to a decimal (divide by 100)
- Step 2: Multiply the decimal by the number
Example: What is 15% of ₹400?
15% = 15 ÷ 100 = 0.15
Now, 0.15 × 400 = ₹60
So, 15% of ₹400 is ₹60.
3) Key Formulas / Rules
Percentage to Decimal:
Percentage ÷ 100 = Decimal
Decimal to Percentage:
Decimal × 100 = Percentage
Percentage of a Number:
(Percentage ÷ 100) × Number = Result
Find Percentage When Part and Whole are Known:
(Part ÷ Whole) × 100 = Percentage
Example: In a Bollywood movie, 120 out of 300 viewers liked the song. What percentage liked it?
Percentage = (120 ÷ 300) × 100 = 40%
So, 40% of the viewers liked the song.
4) Did You Know?
In India, the famous IPL cricket teams often use percentages to show their winning chances! For example, if Mumbai Indians have won 60 out of 100 matches, their winning percentage is 60%. This helps fans and analysts understand team performance quickly.
5) Exam Tips — Common Mistakes & Board Exam Patterns
- Don’t forget to convert the percentage to decimal before multiplying.
- Watch out for the difference between percentage and percentage points. For example, increasing from 20% to 25% is a 5 percentage point increase, but a 25% increase in value.
- Practice questions where you find the whole when given the part and percentage. For example, if 30 is 15% of a number, find the number.
- Board exams often ask word problems related to discounts, profit/loss, population growth, and cricket statistics. Practice these real-life examples.
- Always write the final answer with the % symbol if the question asks for percentage.
Example question from previous exams:
“A shopkeeper gives a discount of 10% on a bicycle priced at ₹5,000. What is the price after discount?”
Solution: 10% of ₹5,000 = (10 ÷ 100) × 5000 = ₹500
Price after discount = 5000 - 500 = ₹4,500
Percentages — Mcq
Percentages — Mnemonic
Mnemonic 1: P.E.R.C.E.N.T — "Please Eat Rasgulla, Celebrate Every Nice Treat!" 🍬🍰
- P - Part (the portion you have)
- E - Equals
- R - Ratio (Part to Whole)
- C - Converted to
- E - Equivalent
- N - Number out of
- T - Total 100 (because percent means per hundred!)
Remember: Percentages are just a way to say “out of 100” — like sharing 100 laddoos among friends! 🎉
Mnemonic 2: "Percent Ka Formula Yaad Rakho, Cricket Mein Score Badhao!" 🏏📊
- Percent (%) = (Part ÷ Whole) × 100
- Imagine: If Virat Kohli scored 75 runs out of 100 balls, his strike rate is like a percentage! 🏏
- Hindi rhyme to remember: "Hissa batao, poora samjho, sau se guna, percent ban jao!"
Mnemonic 3: Funny Acronym — "CHAI" ☕️
- C - Convert percentage to decimal (Divide by 100)
- H - How much is the whole?
- A - Apply the decimal to whole (Multiply)
- I - Identify the part (Result!)
Just like sipping a cup of chai, follow these steps one by one to get the perfect answer! 😄
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