INTERPOLATION AND EXTRAPOLATION
Algebra
INTERPOLATION AND EXTRAPOLATION
This chapter covers the use of interpolation and extrapolation to solve for
unknowns on various types of graphs.
EO 1.17
Given a graph, SOLVE for the unknown using
extrapolation.
EO 1.18
Given a graph, SOLVE for the unknown using
interpolation.
Definitions
Interpolation Interpolation is the process of obtaining a value from a graph or table that is
located between major points given, or between data points plotted. A ratio
process is usually used to obtain the value.
Extrapolation Extrapolation is the process of obtaining a value from a chart or graph that
extends beyond the given data. The "trend" of the data is extended past the last
point given and an estimate made of the value.
Interpolation and Extrapolation
Developing a curve from a set of data provides the student with the opportunity to interpolate
between given data points. Using the curve in the following example, the value of the dependent
variable at 4.5 can be estimated by interpolating on the curve between the two data points given,
resulting in the value of 32. Note that the interpolation is the process of obtaining a value on
the plotted graph that lies between two given data points. Extrapolation is the process in which
information is gained from plotted data by extending the data curve beyond the points of given
data (using the basic shape of the curve as a guide), and then estimating the value of a given
point by using the extended (extrapolated) curve as the source. The above principles are
illustrated in the example that follows.
MA-02
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