explanation

Two types of hydraulic actuators follow the following life behaviors: Actuator type A: A normal distribution N (100.30) Actuator type B: A normal distribution N (125.30) From this information it is requested to calculate a) Which of the two presents greater reliability at 80 days of operation? b) For an average life of each actuator but that follow an exponential type life behavior, what would be in this case the time of change to continue working with a reliability of 80%, indicate which of the two has less reliability c) After how many hours of operation should it be changed? hydraulic actuators if you want to ensure a 90% reliability for each