Since the Cobot's gripper is a critical component, a reliability of 99% is desired for that component. The failure time, in hours, of the cobot's gripper follows a lognormal distribution with t=10.52 and t= 1.44. the gripper is considered a consumable item (i.e., if failed, the gripper is replaced, not repaired.

a. What is the MTTF?

b. At what number of hours of use should the gripper be replaced to meet the desired 99% reliability?