To reduce laboratory costs, water samples from two public swimming pools are combined for one test for the presence of bacteria. further testing is done only if the combined sample tests positive. based on past results, there is a 0.009 probability of finding bacteria in a public swimming area. find the probability that a combined sample from twotwo public swimming areas will reveal the presence of bacteria. is the probability low enough so that further testing of the individual samples is rarely necessary? the probability of a positive test result is is the probability low enough so that further testing of the individual samples is rarely necessary? a. the probability is quite low, indicating that further testing is necessary for all of the combined samples. b. the probability is quite low, indicating that further testing is not necessary for any of the combined samples. c. the probability is quite low, indicating that further testing of the individual samples will be a rarely necessary event. d. the probability is quite low, indicating that further testing of the individual samples will not be a rarely necessary event.