Hair test question

I smoked one Join in July 2012 and or joint in May 2013. I have to take a hair follicle test in early November. I am bald so they will have to take body hair. Those were the only times I smoked since high school 29 years ago. I don't know how far the hair test goes back or even if one joint would show. What are my chances of passing? Thanks for your time!!

Went and took my own. Passed with armpit hair. Body hair grows approx ,3mm per day so that equates going back approx 4 1/2-5 months