probability questions

Question 3 Every morning David went to his office at 6.45 a.m. and was expected to arrive at 7.45 a.m. He believes that the probability that he will arrive before 8.00 a.m. is 0.7 and is independent from day to day. (a) Assuming that David's belief is correct, determine the probability that, during a week, he arrived at his office before 8.00 a.m. is on one or fewer mornings. (3 marks) (b) Calculate the probability of David arriving at his office after 8.00 a.m. for more than two but fewer than six mornings in two weeks. (4 marks)