Question
What is a real life application of a line graph?
Answer
A line graph expresses a relationship between an independent variable, X, and a dependent variable, Y. Often, there is a mathematical function that describes this relationship, such as Y = 3X, which would be shown as a straight line on a line graph, or Y = X^2, which would be a parabola. Often, the mathematical function that defines Y in terms of X is unknown, but we have data that we plot as points on an X-Y plane. By connecting these point, we form line graph that can be useful in determining a value of Y given a value of X. For a real life application, suppose we have 3 data points that relate the gasoline mileage to the speed of a car: Speed = 30 mph, mileage= 30 mpg; speed = 40 mph, mileage = 25 mpg; speed = 60 mph, mileage = 15 mpg. A downward-sloping line graph could be drawn between those 3 points, which would give the value of gasoline mileage for any speed between 30 mph and 60 mph. We could even "extrapolate" or extend the line graph to estimate the miles per gallon at speeds slower than 30 mph or greater than 60 mph. In summary, a line graph is a convenient way to "look up" to value of something based on the value of something else without having to do a lot of calculations. Another useful application is to find the rate of change of a variable with respect to another variable. The rate of change is equal to the slope of the line graph of the function. I hope this answer helped.
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