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| Credit: Pixabay.com |
↪ The quantity whose value depend on the other is called dependent variable.
↪ The quantity which affects the value of dependent variable is called Independent variable (or sometimes control variable).
↪ Generally, independent quantity is plotted on x-axis and dependent quantity is plotted on y-axis.
↪ When two quantities are in direct variation, the graph will always be linear.
Quantity and Cost
Cost of any item depends on its quantity. Therefore between quantity & cost, quantity is independent variable whereas cost is dependent variable.
Example: Draw graph for the following data.
↪ Mark Numbers along horizontal axis.
↪ Mark Cost along vertical axis.
↪ Plot the points : (1,5), (2, 10), (3, 15), (4,20), (5,25).
↪ Join the points. We get a graph that is a line.
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| Graph of Quantity Vs Cost |
Principal and Simple Interest (SI)
SI depends on the Principal borrowed. More the Principal more will be the SI at constant rate of interest. Therefore between Principal & SI, Principal is independent variable whereas SI is dependent variable.Example: Draw graph for the following data.
↪ Mark Deposits along horizontal axis.
↪ Mark Simple Interest along vertical axis.
↪ Plot the points : (1000,80), (2000, 160), (3000, 240), (4000,320) etc.
↪ Join the points. We get a linear graph.
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| Graph of Principal Vs Simple Interest |
Time and Distance
At constant speed, distance traveled is directly proportional to the time taken. Therefore between time & distance, time is independent variable whereas distance is dependent variable.Example: Draw graph for the following data.
↪ Mark time on horizontal axis.
↪ Mark distance on vertical axis.
↪ Plot the points: (6, 40), (7, 80), (8, 120), (9, 160), (10,200).
↪ Join the points. We get a linear graph.
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| Distance-Time Graph |
| Coordinates | |
Coordinate Geometry ➤
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