**Important Concepts and Formulas of Data Handling and Graphs **

1. Data is a collection of numbers,
figures, names or any items collected to give some information.

3. Data can be collected by the
following methods: Taking measurements in experiments, Observing outcomes of
events, conducting surveys, reading statistical publications.

4. The difference between the highest
and the lowest observations is called the range of the data. Range = Value of
the highest observation – Value of the lowest observation.

5. When numerical data is represented as
columns then it is called a bar graph. It is also known as column graph.

6. The double bar graph helps us to
compare or present more than one kind of information.

7. Large data needs to be organized in
groups (classes).

8. The difference between the upper
limit and lower limit of a class is called the class width or size of the
interval.

9. In a histogram, the heights of
various bars are proportional to their frequencies and the bars are drawn
without any gaps between them.

11. When the numerical data is
represented by a sector of a circle, it is called pie chart or pie graph. The
angle of the sector depends upon the value of that item in the data. Angle of
sector = (Value of item/Sum of all items) × 360°.

12. The line graph displays those data
that changes over a period of time. A line graph consists of bits of line
segments joined consecutively.

13. A linear relationship is a relationship
between two variables in which the amount of both the variables increases or
decreases by same quantity. Linear graph is a graph that explains a linear
relationship.

14. Variables used in experiments are of
two types—dependent variable and independent variable.

15. An independent variable is a variable
that is not changed by the other variables. A dependent variable depends on
other factors.

17. Two mutually perpendicular axes
intersect at a point called the origin. Coordinates of the origin are (0, 0).

18. The coordinate axes divide the plane
of a graph paper into four regions called quadrants.