===The construction of the external distribution(''r<sub>external</sub>'') and the RFV===
After modellingmodeling the random and internal possibility distribution, the external membership function, '''''r<sub>external</sub>''''', of the RFV can be constructed by using the following equation:<ref>{{Cite journal|last=Ferrero|first=Alessandro|last2=Prioli|first2=Marco|last3=Salicone|first3=Simona|date=2015|title=Uncertainty propagation through non-linear measurement functions by means of joint Random-Fuzzy Variables|url=http://ieeexplore.ieee.org/document/7151540/|journal=2015 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings|___location=Pisa, Italy|publisher=IEEE|volume=|pages=1723–1728|doi=10.1109/I2MTC.2015.7151540|isbn=9781479961146|via=}}</ref>