✅ What is Average?
The average is the equal share or fair value of a group of numbers.
🔹 Formula to Find Average:
📌 Steps to Find the Average:
1️⃣ Add all the quantities
2️⃣ Count how many quantities are there
3️⃣ Divide the sum by the number of quantities
🔄 Shortcut Words to Remember:
🔸 Average = Total ÷ How Many
Average = Sum of quantities ÷ Total number of quantities
🔸 Think of “Fair Share” – dividing equally among all.
🧠 Remember These Points:
✔ The average may or may not be one of the given numbers.
✔ If the average and number of quantities are known, you can find the total.
Total=Average×Number of quantities
✔ If some numbers and the average are given, you can find the missing number using:
Missing number=(Average×Total items)−(Sum of given numbers)
🎯 Examples:
Example 1:
Find the average of 10, 20, and 30
👉 Sum = 10 + 20 + 30 = 60
👉 Total numbers = 3
👉 Average = 60 ÷ 3 = 20
Example 2:
The average score of 4 students is 75. What is their total score?
Total score = Average × No. of persons
👉 Total = 75 × 4 = 300
Solution:
1. Find the average of the numbers: 12, 18, 24, 16, 10
✏️ Solution Trick:
Add all numbers → 12+18+24+16+10 = 80
Total numbers = 5
Average = 80 ÷ 5
2. Find the average of ₹21, ₹30, ₹45, ₹24, ₹20
✏️ Solution Trick:
Sum = 21+30+45+24+20 = 140
No. of amounts = 5
Average = 140 ÷ 5 =
3. The heights of 4 children are: 125 cm, 130 cm, 128 cm, 117 cm. Find the average height.
✏️ Add all heights: 125 + 130 + 128 + 117 = 500 cm
No. of children = 4
Average = 500 ÷ 4 =
4. A boy scores 85, 78, 90, 92 in four tests. What is his average score?
✏️ Total score: 85 + 78 + 90 + 92 = 345
Tests = 4
Average = 345 ÷ 4 =
5. Find the total if the average of 6 numbers is 23.
✏️ Use formula: Total = Average × Number of quantities
Total = 23 × 6 =
6. The average score of 5 students is 72. What is the total score?
✏️ Total = 72 × 5 =
7. The average of three numbers is 40. Two of the numbers are 36 and 44. Find the third number.
✏️ Total = 40 × 3 = 120
Given: 36 + 44 = 80
Missing number = 120 – 80 =
8. These are the number of books read by five students: 5, 7, 6, 4, 8. Find the average number of books read.
✏️ Total = 5+7+6+4+8 = 30
Students = 5
Average = 30 ÷ 5 =
The average of 4 numbers is 36. Three of the numbers are 40, 32, and 38. Find the fourth number.
✏️ Solution Trick:
Total = 36 × 4 = 144
Given numbers sum = 40 + 32 + 38 = 110
Missing number = 144 – 110 =
A fruit seller sold 120 apples on Monday, 135 on Tuesday, and 105 on Wednesday. How many apples must he sell on Thursday to get an average of 120 apples over 4 days?
✏️ Solution Trick:
Required total for 4 days = 120 × 4 = 480
Apples sold in 3 days = 120 + 135 + 105 = 360
Apples to sell on Thursday = 480 – 360 =
There are 5 shelves of books in a library. Each shelf has the following number of books: 45, 52, 49, 50, and 54. What is the average number of books per shelf?
✏️ Solution Trick:
Total = 45 + 52 + 49 + 50 + 54 = 250
shelves= 5
Average = 250 ÷ 5 =
The average marks of 6 students in a quiz is 72. Five students scored: 70, 74, 69, 76, and 73. What are the marks of the sixth student?
✏️ Solution Trick:
1.Total marks = 72 × 6 =
2. Sum of five marks = 70 + 74 + 69 + 76 + 73 =
Sixth student’s marks = (1 – 2 )=
The average temperature of 7 days was 28°C. If the total temperature for 6 days is 165°C, what was the temperature on the 7th day?
✏️ Solution Trick:
1.Required total for 7 days = 28 × 7 =
2.Temperature for 6 days =
7th day’s temperature = (1 – 2)=