For the 2009 NFL Season,data Are Available on Such Variables

Multiple Choice

For the 2009 NFL season,data are available on such variables as the total yards gained by passing and by rushing for each of the 32 teams.The following is a scatter plot of the two variables,PassYds and RushYds. It was found that the correlation between the two variables was r = -0.313.In a test of hypothesis of H₀: = 0 against H_a:  0,with  = 0.05,the value of the test statistic and its degrees of freedom are,respectively,

A) t = -1.81 anddf = 31.
B) t = -2.04 and df = 30.
C) t = -2.04 and df = 31.
D) t = -1.81 and df = 30.
E) This cannot be determined without knowing SSM and SST.