Resistance as a Random Variable?

X1088LoD

I've been asked to model a resistance as a random variable. I am not exactly sure what that entails, but I was hoping someone might give me a little bit of insight.

I have one resistance that is oscillating sinusoidally, and that produces a U shaped probability distribution. As is shown in one of the attached pictures. However, I am adding another resistance in series to that, which would generate the probability density function, also attached, that has the spike in the middle. (Two resistors in series means I can convolve the two PDF's together to get the outcome). By visual estimation, I would assume that another sinusoid PDF convolved with the original sinusoid PDF would produce that effect.

Any tips or suggestions is much appreciated.

Attached Thumbnails