Heart failures are due to either natural occurrences (81%) or outside factors (19%). Outside factors are related to induced substances (73%) or foreign objects (27%). Natural occurrences are caused by arterial blockage (56%), disease (27%), and infection (e.g., staph infection) (17%). Round your answers to four decimal places (e.g. 98.7654).
a) Determine the probability that a failure is due to induced substance.
b) Determine the probability that a failure is due to disease or infection.