Reliability analysis question

Stage 1 Stage 2 Q7 0.6 Consider product design, you know design and the success rate of each part 0.4 0.2 0.9 Reliability analysis (3 things): 1. Reliability is the success rate of the system. This value is between 0 and 1. In the design, this value (reliability), the larger, the better. 2.For the series system, the success rate of the system is the product of the stage success rates. 3.For the parallel system: (a) find the failure rate of each branch first; (b) then, find the failure rate of the stage; () finally find the success rate of the stage; (because, to find system reliability, we need stage success rate.)