Nathan had an infection, and his doctors wanted him to take penicillin. because nathans father and paternal grandfather were allergic to penicillin, nathan has a 75% chance of having the same allergy. the doctor performed a skin test to see whether nathan would react to it. the test is 98% accurate. if the test predicts that nathan is not allergic to penicillin, what is the probability after the test that nathan is not allergic to the drug