Class 8 Maths Introduction to Graphs Notes & MCQs

Introduction to Graphs – Quick Notes (Class 8 )

A graph is a visual representation of data. It shows the relationship between two variables.

Line Graph
- Uses points joined by lines to show trends over time.
- Example: Temperature vs Days
Bar Graph
- Uses rectangular bars to compare quantities.
- Height/length = value
Histogram
- Similar to bar graph but continuous data in intervals.
Pie Chart
- Circle divided into sectors, each representing proportion of total.
Cartesian Graph
- Uses x-axis and y-axis to plot points ( $x, y$ x,y).

Q: What is a graph?
A: A visual representation of data showing relationship between variables.
Q: Which axis represents independent variable?
A: x-axis ✅
Q: Which axis represents dependent variable?
A: y-axis ✅
Q: What type of graph is used to show trends over time?
A: Line graph ✅
Q: Bar graph is used for?
A: Comparing quantities ✅
Q: Histogram shows?
A: Continuous data in intervals ✅
Q: Pie chart represents data in?
A: Proportion / percentage ✅
Q: Point (3,5) → which is x and which is y?
A: x = 3, y = 5 ✅
Q: In line graph, points are joined by?
A: Lines ✅
Q: In bar graph, bars represent?
A: Values of data ✅
Q: Total percentage in pie chart?
A: 100% ✅
Q: Cartesian plane has how many axes?
A: 2 (x and y) ✅
Q: What is independent variable?
A: Variable we control / choose ✅
Q: What is dependent variable?
A: Variable that depends on independent variable ✅
Q: Line graph vs Bar graph → which shows trend?
A: Line graph ✅
Q: Histogram vs Bar graph → difference?
A: Histogram → continuous intervals; Bar graph → discrete values ✅
Q: How to label axes?
A: Independent variable → x-axis, Dependent variable → y-axis ✅
Q: Can we connect points in bar graph?
A: No ✅
Q: Cartesian coordinates of origin?
A: (0, 0) ✅
Q: Which graph shows part-to-whole relationship?
A: Pie chart ✅