**Data:** Numerical observations collected by an observer is called data (raw data).

**Frequency:** The number of times an observation occurs in the given data is called the frequency of the observation.

**Frequency Distribution:** A way of presenting data that exhibits the values of the variable and corresponding frequencies is called a frequency distribution.

**Range:** The difference between the highest and the lowest values of observation is called range.

i.e., Range = Highest observation – Lowest observation

**Class-mark:** The mid-point of a class-interval is called class-mark.

### Data handling :

Data handling is referred to the procedure done to organize the information provided in order to perform mathematical operations on them.

### Pie Charts

A** pie chart** shows the relationship between a **whole circle and its parts**. The circle is divided into sectors. The **size of each sector **is **proportional **to the **information** it represents. Pie charts are also known as **circle graphs**.

### Pictographs

A **pictograph** is the pictorial representation of data using symbols.

For example, If 10 Apples were sold in January, 40 were sold in February, 25 were sold in March, and 20 were sold in April. We can represent the given data as a pictograph as given below:

### Bar Graphs

A bar graph is a representation of data using a rectangular bars that are having heights that are proportional to the values that are represented by them.

### Multiple Bar Graphs

Multiple bar graphs is a bar graph which is used for comparing more than one kind of information.

Example:

**Histogram:** Grouped data can be presented using the histogram. A histogram is a type of bar diagram, where the class intervals are shown on the horizontal axis and the height of the bars show the frequency of the class interval. Also, there is no gap between the bars as there is no gap between the class intervals.

**Probability:** Probability is the possibility and impossibility of an event (E).

ncert solutions