It is estimated that 82% of homes have working smoke detectors. On average, 22% of fires result

Question:

It is estimated that 82% of homes have working smoke detectors. On average, 22% of fires result in fatalities, but the presence of a working smoke detector cuts the risk to just 7%.
a. If a random fire resulted in a fatality, what is the probability that the house had a working smoke detector?
b. In homes without a working smoke detector, what is the risk of fatalities? 5.3.2 Extensions