9. Consider the data with Analysis in the following computer output:

Level N Mean St Dev

A 6 86.999 5.325

B 5 76.167 6.555

C 6 80.000 9.230

D 7 69.333 6.154

Sources DF SS MS F P

Groups 3 1053.84 351.28 7.27 0.002

Error 20 966.85 48.34

Total 23 2020.69

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

Degrees of freedom=