Class7 Maths : Mean, Median, Mode and Range

1. Mean (Average)

Definition

The mean is the average of a group of numbers.

Formula

Mean = Sum of all observations ÷ Number of observations

Explanation

To find the mean, add all the values and divide the total by how many values are there.

Example 1

Find the mean of: 4, 6, 8, 10

Solution:
Sum = 4 + 6 + 8 + 10 = 28
Number of values = 4
Mean = 28 ÷ 4 = 7

Answer: Mean = 7

Example 2

Find the mean of: 12, 15, 18, 10, 5

Solution:
Sum = 60
Number of values = 5
Mean = 60 ÷ 5 = 12

Answer: Mean = 12

Real-Life Uses of Mean

• Average marks of a student
• Average temperature of a week
• Average salary in an office
• Average runs of a cricket player

---

2. Median

Definition

The median is the middle value when the data is arranged in order.

Steps to Find Median

1. Arrange the data in ascending order
2. Find the middle value
   • Odd number of values → middle one
   • Even number of values → average of two middle values

Example 1

Find the median of: 5, 2, 9, 1, 7

Solution:
Ordered data: 1, 2, 5, 7, 9
Middle value = 5

Answer: Median = 5

Example 2

Find the median of: 10, 20, 30, 40

Solution:
Ordered data: 10, 20, 30, 40
Middle values = 20 and 30
Median = (20 + 30) ÷ 2 = 25

Answer: Median = 25

Real-Life Uses of Median

• Finding middle income of people
• Property price analysis
• Sports rankings
• Population studies

📌 Median is useful when there are very high or very low values in data.

---

3. Mode

Definition

The mode is the value that occurs most frequently in the data.

Formula

There is no formula for mode.

Example 1

Find the mode of: 2, 4, 6, 4, 8

Solution:
4 appears twice

Answer: Mode = 4

Example 2

Find the mode of: 5, 7, 5, 9, 5, 11

Solution:
5 appears three times

Answer: Mode = 5

Real-Life Uses of Mode

• Shoe companies find the most common shoe size
• Shops find the most sold item
• Schools find the most popular subject
• Clothing brands decide which sizes to produce

---

4. Range

Definition

The range is the difference between the highest and lowest values.

Formula

Range = Highest value − Lowest value

Example 1

Find the range of: 3, 7, 10, 2, 8

Solution:
Highest = 10
Lowest = 2
Range = 10 − 2 = 8

Answer: Range = 8

Example 2

Find the range of: 15, 25, 30, 10

Solution:
Highest = 30
Lowest = 10
Range = 30 − 10 = 20

Answer: Range = 20

Real-Life Uses of Range

• Difference between highest and lowest temperature
• Variation in marks of a class
• Weather changes
• Comparing test scores