Hi I need help in this, but we must to have present that we are speaking about Stochastic processes it is the most important

Based on stochastic processes: Suppose a Poisson process Nt represents the number of failures in a switch where there are known to be five failures per day: iii. If they presented two failures in the middle ofthe period, what is the probability that three more failures will occur in the second part of the period? iv. What is the expected time for the ninth failure to arrive