Find the obligatory probability.
1. Shopper Trak is a concealed electric eye designed to count the number of shoppers entering a store. When two shoppers arrive the store together one walking in front of the other, the following possibilities apply. There is a 0.98 possibility that the first shopper will be detected and a 0.94 probability that the second shopper will be detected and a 0.93 probability that both of them will be detected by the device. Explain what is the probability that the device will detect at least one of the two shoppers entering together?
2. A statistics professor has initiate that the probability is 0.74 that a student gets a B- or above for the final examination. He as well found that the probability of 0.67 that a student gets a B- or above for both the final exam and the course. If a arbitrarily selected student has already gotten a B- or above for the final exam taken yesterday what is the probability he will get a B- or above for the course when the grade report arrives next week?