An aircraft emergency locator transmitter (ELT) is a device designed to transmit a signal in the case of a crash. Company A makes 80% of the ELTs, company B makes 15% of them, and company C makes the other 5%. The ELTs made by A have a 4% rate of defects, Bs ELTs have a 6% rate of defects, and Cs ELTs have a 9% rate of defects. If a randomly selected ELT is tested and is found to be defective, find the probability that it was made by company A.