Consider the data with analysis shown in the following computer output: Level N Mean StDev A 7 85.904 4.905 B 5 76.167 6.555 5 80.000 9.230 D 7 69.333 6.154 Source DF SS MS F P Groups 3 999.12 333.04 7.53 0.002 Error 20 884.23 44.21 Total 23 1883.35 What is the pooled standard deviation? What degrees of freedom are used in doing inferences for these means and differences in means? Round your answer for the pooled standard deviation to two decimal places. The pooled standard deviation is i degrees of freedom =