Transformation of Averageif formula from Excel in QS

[JohBeNeLux]

Hi everybody, 

I am new in working with QS and I try to transform my excel function with which I calculated my base sales into a formula which works for QS. 

=AVERAGEIF(K4:AF4;"<"&(AVERAGE(K4:AF4)+STDEV(K4:AF4))

Can someone help me with this please?

Thank you.