Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 118.9136 6.3516 18.722 < 2e-16 *** price -7.9079 1.0960 -7.215 4.42e-10 *** adv_cost 1.8626 0.6832 2.726 0.Using the same hypothesis test or computing with gretl, the t-ratio for the advertising costs (adv_cost) is ________