You Decide to Estimate the Following Quarterly Sales Forecasting Model

You decide to estimate the following quarterly sales forecasting model for new boat sales in your local county:
The equation is estimated using quarterly data on new boat sales in the county from 2001III -2007IV ( t = 1,..., 26). The variable D is a dummy variable for the second quarter, which is the "season" for selling new boats: D = 1 in the second quarter, and 0 otherwise. The results of the estimation are:

-At the 1 percent level of significance, the critical value of the t-statistic is _______. The parameter estimate of a ________ (is, is not) statistically significant. The parameter estimate of b ________ (is, is not) statistically significant. The parameter estimate of c ________ (is, is not) statistically significant.