Consider the data with analysis shown in the following computer output:

Level	N	Mean	StDev
A	6	85.906	5.157
B	5	76.167	6.555
C	6	80.000	9.230
D	7	69.333	6.154

Source	DF	SS	MS	F	P
Groups	3	939.09	313.03	6.53	0.003
Error	20	958.04	47.90
Total	23	1897.13

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 Enter your answer; degrees of freedom =