If a program P calls two subprograms P1 and P2 and P1 can fail 50% of the time and P2 can fail 40% of the time, what is the failure rate of program P?
- A. 50%
- B. 60%
- C. 70%
- D. 10%
Answer: C. 70%
Explanation: P fails if P1 fails OR P2 fails. P(Fail) = P(F1 u F2) = P(F1) + P(F2) - P(F1 n F2) = 0.5 + 0.4 - (0.5*0.4) = 0.9 - 0.2 = 0.7 = 70%.