A construction firm purchased 3 tractors from a certain company. At the end of 5th year, let E1, E, and E, denote, respectively, the vents that tractors no. 1, 2, and 3 are still in good operational condition. a) Define the following events at the end of the 5th year, in terms of E1, E2, and E3, and respective complements: A= only tractor no. 1 is in good condition B= just one tractor is in good condition C= at least one tractor is in good condition b) Past experience indicates that the chance of a given tractor manufactured by this company having a useful life longer than 5 years is 60% (meaning each tractor has 60% chance to be in good condition after 5 years). If one tractor needs to be replaced (meaning it is not in good condition) at the end of 5th year, the probability of replacement for one of the other 2 tractors is 60%. If 2 tractors need to replaced, the probability of replacement of the remaining one is 80%. Calculate the probabilities of Events A, B, and C.