Will cocaine be out of my system?

I did probably less than .5 grams of cocaine on 3/18, i am not a habitual user and have not done the drug in at least 6 months beforehand. I have a drug test on 4/6. That's almost three weeks. I do not know weather or not the test i am going to be given tests for metabolites or not but assuming it is if i drink plenty of water and exercise a lot what are my chances of passing? I am of average weight and height, maybe slightly overweight. i may have a pretty slow metabolism. what are my chances of passing?