Notes On Data Value - CBSE Class 7 Maths
Different forms of representative or central value are used to represent and describe different forms of data. One of the representative values is the “Arithmetic Mean”. Arithmetic mean Arithmetic mean is a number that lies between the highest and the lowest values of the data. Arithmetic mean or Average = $\frac{\text{Sum of observations}}{\text{Number of observations}}$ Note that we need not arrange the data in ascending or descending order to calculate arithmetic mean. Range Range is calculated by subtracting the lowest observation from the highest observation of a data. It gives an idea of the spread of the observations. Range = Highest observation – Lowest observation Mode Mode of a set of observations refers to the observation that occurs most often. Steps to calculate the mode of a data: Step 1: Arrange the data in ascending order. Step 2: Tabulate the data in a frequency distribution table. Step 3: The observation with a greatest frequency is the mode. Median Median refers to the value that lies in the middle of the data with half of the observations above it and the other half of the observations below it.  Steps to calculate the median of a data: Step 1: Arrange the data in the ascending order. Step 2: The value that lies in the middle such that half of the observations lie above it and the other half  below it will be the median. The mean, mode and median are the representative values of a group of observations or data, and lie between the minimum and maximum values of the data. They are also called the measures of the central tendency.

#### Summary

Different forms of representative or central value are used to represent and describe different forms of data. One of the representative values is the “Arithmetic Mean”. Arithmetic mean Arithmetic mean is a number that lies between the highest and the lowest values of the data. Arithmetic mean or Average = $\frac{\text{Sum of observations}}{\text{Number of observations}}$ Note that we need not arrange the data in ascending or descending order to calculate arithmetic mean. Range Range is calculated by subtracting the lowest observation from the highest observation of a data. It gives an idea of the spread of the observations. Range = Highest observation – Lowest observation Mode Mode of a set of observations refers to the observation that occurs most often. Steps to calculate the mode of a data: Step 1: Arrange the data in ascending order. Step 2: Tabulate the data in a frequency distribution table. Step 3: The observation with a greatest frequency is the mode. Median Median refers to the value that lies in the middle of the data with half of the observations above it and the other half of the observations below it.  Steps to calculate the median of a data: Step 1: Arrange the data in the ascending order. Step 2: The value that lies in the middle such that half of the observations lie above it and the other half  below it will be the median. The mean, mode and median are the representative values of a group of observations or data, and lie between the minimum and maximum values of the data. They are also called the measures of the central tendency.

Next