Aproduction line has three machines a, b, and c, with reliabilities of .99, .96, and .93,respectively. the machines are arranged so that if one breaks down, the others must shut down. engineers are weighing two alternative designs for increasing the line’s reliability. plan 1 involves adding an identical backup line (i. e., a series backup), and plan 2 involves providing a backup for each machine (i. e., a parallel backup). in either case, three additional machines (a, b, and c) would be used with reliabilities equal to the original three.

a. which plan will provide higher reliability?
b. explain why the two reliabilities are not the same.