Students can go through AP 8th Class Maths Notes Chapter 15 Introduction to Graphs to understand and remember the concepts easily.
Class 8 Maths Chapter 15 Notes Introduction to Graphs
→ Graphical presentation of data is easier to understand.
→
- A bar graph is used to show comparison among categories.
- A pie graph is used to compare parts of a whole.
- A Histogram is a bar graph that shows data in intervals.
→ A line graph displays data that changes continuously over periods of time.
→ Aline graph which is a whole unbroken line is called a linear graph.
→ For fixing a point on the graph sheet we need, x-coordinate and y-coordinate.
→ The relation between dependent vari-able and independent variable is shown through a graph.
→ Graphs : Graphs are visual representations of collected data.
→ What is the purpose of graph ?
Purpose of graph is to show numerical facts in visual form so that they can be understood quickly, easily and clearly.
The following figure shows marks of a child in SA I, SA II, SA III, which can be represented by bar graph.
→ Pie – graph or Circle graph: Pie graph is another kind of graph to represent data in sectors.
Histogram : Histogram is a bar graph that expresses data in intervals, it has adjacent bars over the intervals
The following figure illustrates the distribution of the data given below table.
| Weight (kg) | 40 – 45 | 45 – 50 | 50 – 55 | 55 – 60 | 60 – 65 |
| Number of persons | 4 | 12 | 13 | 5 | 5 |
→ If gaps are there in given intervals, then there will be gaps in bars of Histogram. Otherwise there wont be any graps.
→ Line graph : A line graph displays data that changes continuously over periods of time.
Ex : distance – speed ; V – T (velocity time graph) t – t (time, temperature) graph.
In this if time is taken on horizontal line (X – axis the other one temperature / velocity etc., will be taken on Vertical line (called Y – axis)
