Soil or water ph is measured on a scale of 0–14. a ph reading below 7 is considered acidic, while a ph reading above 7 is basic. the ph level of water provided by a type of spray tank irrigation is equally likely to be either 6.8, 6.9, 7.0, 7.1 or 7.2. let e1 denote the event that at the next irrigation the water ph level measurement is at most 7.1, and e2 the event that the water ph level is at least 6.9. find the probabilities p(e1), p(e2), p(e1 ∩e2), p(e1 ∪e2), p(e1 −e2), and p((e1 −e2)∪(e2 − akritas, michael. probability & statistics for engineers and scientists with r (pearson modern classics for advanced statistics series) (p. 71). pearson education. kindle edition.