**Constant:**

A quantity which can be assuming only one value is called a constant. It is usually denoted by the first letters of alphabets .

**For Example:** Value of and value of .

**Variable:**

A quantity which can vary from one individual or object to and other is called a variable. It is usually denoted by the last letters of alphabets .

**For Example:** Heights and Weights of students, Income, Temperature, No. of Children in a family etc…

**Continuous Variable:**

A variable which can assume each and every value within a given range is called a continuous variable. It can occur in decimals.

**For Example: **Heights and Weights of students, Speed of a bus, the age of a Shopkeeper, the life time of a T.V etc…

**Continuous Data:**

Data which can be described by a continuous variable is called continuous data.

For Example: Weights of 50 students in a class.

**Discrete Variable:**

A variable which can assume only some specific values within a given range is called discrete variable. It cannot occur in decimals. It can occur in whole numbers.

For Example: Number of students in a class, number of flowers on the tree, number of houses in a street, number of chairs in a room etc…

**Discrete Data:**

Data which can be described by a discrete variable is called discrete data.

**For Example:** Number of students in a college.

**Quantitative Variable:**

A characteristic which varies only in magnitude from on individual to another is called quantitative variable. It can be measurable.

**For Example:** Wages, Prices, Heights, Weights etc…

**Qualitative Variable:**

A characteristic which varies only in quality from one individual to another is called qualitative variable. It cannot be measured.

**For Example:** Beauty, Marital Status, Rich, Poor, Smell etc…