Please help with the problem!

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

Which of the following is the result of expanding the series

You eat $0.85 for every cup of hot chocolate you sell. how many cups do you need to sell to earn $55.25