I need the answers for all three of those

Aparallel system functions whenever at least one of its components works. consider a parallel system of n components, and suppose each component works independently with probability 0.5. find the conditional probability that component n works given that the system is working

Identify a1 and r for the geometric sequence an= -256(-1/4) n-1

Matt had 5 library books. he checked out 1 additional book every week without retuening any books. whats the matching equation