An auditor for a county government would like to develop a model to predict the county taxes based on the age of a single-family houses. A random sample of 19 single-family houses bas been selected, with the following results:

Taxes Age

925 1

870 2

809 4

720 4

694 5

630 8

626 10

562 10

546 12

523 15

480 20

486 22

462 25

441 25

426 30

368 35

350 40

348 50

322 50

a) Set up a scatter diagram between age and county taxes.

b) State the liner regression equation.

c) State the quadratic regression equation. Determine whether there is a significant overall relationship between age and county taxes at the 0.05 level of significance.

d) Determine which one of the models is better to be used for predicting the average county taxes for a house. Use significant level 0.025.

e) Using appropriate plots for each model determine whether any of the regression assumptions have been violated (residual analysis).

f) Using the quadratic regression equation Predict the average county taxes for a house that is 20 years old.