A company places a rush order for wire of two thicknesses. Consignments of each thickness are to be sent immediately when they are available. Previous experience suggests that the probability is $0.8$ that at least one of these consignments will arrive within a week. It is also estimated that, if the thinner wire arrives within a week, the probability is $0.4$ that the thicker wire will also arrive within a week. Further, it is estimated that, if the thicker wire arrives within a week, the probability is $0.6$ that the thinner wire will also arrive within a week.
a. What is the probability that the thicker wire will arrive within a week?
b. What is the probability that the thiner wire will arrive within a week?
c. What is the probability that both consignments will arrive within a week?