A bank has a test designed to establish the credit rating of a loan aplication. If the persons, who defaults (D), 90% fail the test (F). Of the persons, who will repay the bank (ND), 5% fail the test. Furthermore, it is given that 4% of the population is not worthy of credit (i.e. defaulters). Give that someone failed the test, what is the probability that he actually will default ? (When given the loan)