D. Develop the null and alternative hypothesis for the Di coefficient (average price per patient - one-tail test), the b2 coefficient (average price charged by competition - one tail test) and the b3 coefficient (advertising variable - two tail test). Briefly describe when it is appropriate to use a one-tail test relative compared to a two-tailed t-test? Use a t-test to determine the level statistical significance for each individual independent variables at the 95 and 99 percent confidence levels