A group of chemists is monitoring 20 different locations of a river for its biochemical oxygen demand (BOD). BOD (ppm) 26 88 45 15 16 7 77 19 33 30 50 60 19 80 23 66 55 31 107 17 a. If we consider these 20 locations to be the population of interest, what is the mean of the population? b. The chemists are planning to choose 5 sampling points selected at random from the list. The BOD values for the 5 sampling points of the river are, 31 23 15 77 60 If these 5 values were used to estimate the mean BOD for all 20 locations, what would the sampling error be? c. What is the range of possible sampling error if 5 sampling points are selected at random from the population?