A researcher specified a linear regression equation as Y=a+bx1+cx2+dx
3+e and estimated it using data from 64 observations and obtained the regression output given in the table below.
Explanatory Variable Coefficient Estimates t-statistics
Constant/Intercept 94.5 4.122
x1 - 1.46 2.703
x2 - -4.10 -3.485
x3 - 2.52 2.400
a. what are the degrees of freedom for determining the critical t value of this model.