How long would it take to pass a urine test after one hit of marijuana?

THC is one of the numerous cannabinoid chemicals present in

marijuana as well as the primary psychoactive ingredient. Cannabinoid metabolites appear in urine within two to four hours

after smoking marijuana and may persist up to 30 days (at the 50

ng/mL cut-off concentration) depending upon a person's previous

pattern of abuse. In general, infrequent use of marijuana may only

be detected for 1-3 days after use. Regular use, several times

per week, may be detected for 7-10 days, while chronic use of

marijuana may be detectable for up to 30 days. Routine passive

inhalation to marijuana will not cause a positive urine drug test

for THC at a 50 ng/mL screening cut-off concentration.

This is cut and paste from Redwood Toxicology website. This is the company my probation uses for drug screens.