Observations are taken on sales of a sales of a certain mountain Bike in 28 sporting goods store. The regression model was Y= total sales ( thousands of dollars), X,= display floor space ( square meters), X2= competitors' advertising ( thousands of dollars), X3= advertised price (dollar per unit)

Predictor Coeffient SE Tcalc p-value

Intercept 1,280.7 385.1

Floor space 11.135 1.66

Competing Ads -6.667 3.981

Price 00.14503 0.0327

B) What is the critical value of students T in Appendix D for a two-tailed test at a=.01