Sec 6.2 Interpreting Graphs

Estimating a value between two given values.�

Interpolation should only be used when it makes sense to have values between given values.�

Interpolate

Example #1A weather balloon recorded the air temperature at different altitudes. The data approximately represent a linear relationship.

Altitude (meters) 400 800 1200 1400

Temperature(Celsius)

12.19 10.38 8.57 7.67

Sec 6.2 Interpreting Graphs

Sec 6.2 Interpreting Graphs Page 1

a) Interpolate the approximate value for the air temperature when the balloon was at a height of 600 m

What was the approximate altitude of the balloon at an air temperature of +6 degrees Celsius?

Is it possible to interpolate a precise value for the air temperature when the altitude is 1050.92?

Is it appropriate to join the points with a straight line?

Example #2

Estimate a value beyond a given set of values.�

Should only be used when it makes sense to have values beyond given values.�

Extrapolate

The value of a computer decreases over the years since its purchase. The grid shows the value of the computer after each corresponding year.

Time (yrs) 1 2 3

Value ($) 800 600 400

After what period of time is the computer worth nothing?

What was the original cost of the computer?

Does this graph have a boundary for how far you can extrapolate?

Practice Exercises:

Sec 6.2 Interpreting Graphs Page 2

Sec 6.2 Interpreting Graphs Page 3

Sec 6.2 Interpreting Graphs Page 4