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7a) (5 pts) As the operations manager of a critical mail sorting facility, you have the option of utilizing three sorting machines (R1, R2, and R3) with reliabilities of 0.8.0.85, and 0.9, respectively a) What will be the reliability of the mail sorting process if you use the machines in the following arrangement? R1 -0.8 R1 - 0,8 R2 = 0.85 R2 = 0.85 R3 = 0.9 7b. (5pts) As a design engineer you need to obtain 99.9% reliability. The first part has a reliability factor of 99.99%. What level of reliability does the series part require to achieve 99.9% overall reliability? 7c. (5pts) The design engineer in question 7b needs to improve the overall system reliability by adding another part in parallel to the unit calculated in question 7b. The objective is to achieve an overall system reliability of 99.95%. What reliability must the parallel part have to meet this objective