Negative Value should be Positive Value when Automatic Range define

Dear sir / Madam

If A5 column change the value than Range also be changed based on A5 Value and Average Value to be mention in B5 Column
For Example A5 Column Shows 18800 than Range to be select as Column B29 to B52 and answerd should be 91.25
If A5 column Shows 18600 than Range to be select as Column B25 to B52 and answered should be 92.32
Negative and Zero Values in Product Value column should be consider as Positive Value

Note Negative value should be calculate with Positive value When Range found any Negative Value (in our sheet B36 shows -80 value. when calculation done it's should be consider as positive 80

Sir ! I want that when the average sum is calculated based on the criteria mentioned in column A5 (in our example 18700), then the summation formula has to count all the negative value as a positive value in comparison.
( in our example the Average summation from B 27:B 52 will be 90.57 although there is negative value in coloumn B:36 i.e. -80) The average summation function will have to calculate the average in positive Value if there is negative value in Range)

Dear Sir

Exact Answer as per Requirement Thank you Very much