Please solve this ASAP the answer doesn't have to be pretty

Question 3: [3+2+3=8] a) A plane lands 4 times i a day in different anports. The successful landing of the plane 1s 90%. Find the probability that, in a randomly selected day 1. At least 3 times it lands successfully. i1. At best 3 times 1t lands successiully. 111, All the times it fails to land successfully. b) Suppose that you are looking for a teacher at your college who lives within five miles of you. You know that 25% of the 200 teachers do live within five miles of you. You randomly contact teacher from the college until one says he or she lives within five miles of you. What is the probability that you need to contact at least four people? c) After receiving a large shipment of computer chips. 800 chips are randomly selected. If 3 or fewer defective chips are found. the entire lot is accepted without inspecting the remaining chips in the lot. If 4 or more chips are defective, every chip in the entire lot is carefully inspected at the supplier's expense. Assume that the true proportion of nonconforming computer chips being supplied 1s 0.001. Find the probability that the lot will be accepted