yes, it will. that is the reason why so many drug addicts shave their heads all the time. whenever you smoke weed, or do any other kind of drug it will show up unless you cut your hair off from the exact spot of where your hair roots were when you did the drug.
(root)-------------- (that is your hair when you smoked weed)
--------------(where the root was)--------------
(growth)
you must cut your hair at this point:
--------------- (where the root was)--------------
(growth) (cut right before where the root was)
that is the only way to get rid of any trace of marijuana.
unfortunately you probably don't know where your hair root was so if you REALLY want this job, i'd say get ready for a buzz cut, and just grow it out.
only in the hair that is new that did not exist before you smoked will there be no trace of weed.
hope that helped!! and good luck with the job.