(a) Draw a scatter diagram of the data. What type of relation appears to exist between x and y?

(b) Find the quadratic regression equation y̅ = b0 + b1x + b2x2.

(c) Draw a residual plot against the fitted values, x, and x2. Also, draw a boxplot of the residuals. Are there any problems with the model?

(d) Interpret the coefficient of determination.

(e) Does the F-test indicate that we should reject H0: β1 = β2 = 0? Is either coefficient not significantly different from zero?

(f) Construct and interpret 95% confidence and prediction intervals for x = 4.

x ______________________y

1 ............................... 25.1

1.5 ............................ 19.3

2.1 ............................ 13.9

3.6 ............................8.5

4.3 ............................7.7

5.9 ............................ 12.9

6.2 ............................ 14.3