Looking for advice on Pooled Standard Deviation between Minitab and MS Excel

[virachakas]

Hello guys..

I have been working in a excel file to be able to create EWMA graphs, but I'm stuck with the pooled standard deviation, the standard deviation that the excel gave me is different than the calculated at Minitab. I have been looking on Internet for a formula that match the Minitab result without success til now..

Does anyone has get it on Excel??

 

[Miner]

From Minitab help.