__10.Observation__

__i) Variable and Constant:__
1. A measurable quantity which can vary from one individual to another is
called a

**‘variable’**. Examples are heights and weights of students in a class, prices of commodities, number of children in a family, etc. It is denoted by the last letters of alphabets, i.e., x, y, and z.
2.

**‘Constant’**is a quantity which can assume only one value. Examples are p = 3.14159,*e*= 2.71828, etc. It is usually denoted by the first letters of alphabets, i.e., a, b, c, d, …

__ii) Continuous or Discrete Variables:__
1. A variable which can assume any value within a given range is called
a

**continuous variable**. For example, the heights and weights of students, temperature, speed, etc. the height of a student can be 62”, 62.5” or 62.45”.
2. A variable which can assume only some specific values within a given
range is called a

**discontinuous or discrete variable**. For example, the number of houses in a town, number of children in a family, number of students in a class, etc. a discrete variable takes on values which are integers or whole numbers like 0,1,2,3,4,5, … but cannot be 2.5, 3.3, 3.91, 14.235, etc. There cannot be 4.5 houses in a town or 10.15 number of students in a class, etc.

__iii) Quantitative and Qualitative Data:__
1.

**Quantitative variables**are heights, weights, temperature, speed, etc.
2.

**Qualitative data**are described by qualitative variables, such as marital status, religion, colour, race, etc.
## 0 comments: