Consider the regression model fit to the X-ray inspection data in Exercise 12-15. Use rads as the response.

(a) Test for significance of regression using α = 0.05. What is the P-value for this test?

(b) Construct a t-test on each regression coefficient. What conclusions can you draw about the variables in this model? Use α = 0.05.

Exercise 12-15

An article in Electronic Packaging and Production (2002, Vol. 42) considered the effect of X-ray inspection of integrated circuits. The rads (radiation dose) were studied as a function of current (in milliamps) and exposure time (in minutes).