Asparrow flies to see a friend at a speed of 4km/h. his friend is out, so the sparrow immediately returns home at a speed of 5km/h. the complete journey took 54 minutes. how far away does his friend live?

Suppose that 3% of all athletes are using the endurance-enhancing hormone epo (you should be able to simply compute the percentage of all athletes that are not using epo). for our purposes, a “positive” test result is one that indicates presence of epo in an athlete’s bloodstream. the probability of a positive result, given the presence of epo is .99. the probability of a negative result, when epo is not present, is .90. what is the probability that a randomly selected athlete tests positive for epo? 0.0297