I am not completely clear on what you're hoping to change or achieve in the workbook attached. Can you mockup your expected results, giving us an idea of what the viz should look like when completed?
I am not clear on what is counting a 1 where you want 5... any more detail you can add to clarify (screenshots, descriptions, etc.) will be helpful for getting you the assistance you need.
Happy analyzing with Tableau!
thank you for your answer.
I found a solution this morning but would like to explain the request and solution in case someone else faces the same problem.
I searched the Forums for "how to create a bell chart" and found the hint to use histogram to create bins, adapted the size of the bins to 10%.
The measure was assigned to columns and rows was automatically filled with COUNT([MEASURE]).
I searched for a possibility to get the weight of Quantity influencing the %.
It's so pretty simple that I can't understand why I haven't had the idea instantly ...
Instead of using COUNT([MEASURE]) I only have to use
SUM([Quantity]) / TOTAL(SUM([Quantity])) for the percent to get the % distribution of Quanties. The bins still work as expected.
and attached the TBWX as file