and total triglyceride (X2) concentrations in the sample, plus the presence or absence of a certain sticky component called sinking pre-beta, or SPB (X3), which was coded as 0 if absent and 1 if present. The data obtained are shown in the table on page 247 and the accompanying computer results. a. Test whether X1, X2, or X3 alone significantly helps in predicting Y. b. Test whether X1, X2, and X3 taken together significantly help to predict Y. c. Test whether the true coefficients of the product