Hi, can anyone help me out or give me a hint?
"Abe owns an apple orchard. He is having pest problems, and he has a scanner at his disposal which allows him to check if a tree is infested or not. He knows that 25% of all trees are infested. The technology is correct 80% of the time. If he checks 100 trees at random, how many can he expect the scanner will determine to be pest-free?" This question is really confusing because there are 2 probabilities. My guess is that out of the 75 trees that are not infested in the random sample the scanner will say that 60 trees are pest-free and out of the 25 that we would expect to be infested the scanner would say 5 are not infested. So 65 trees is that right?