The following frequency table shows the classification of 58 landfills in a state according to their concentration of the three hazardous chemicals arsenic, barium, and mercury.
If a landfill is selected at random, find the probability that it has: (a) A high concentration of barium. (b) A high concentration of mercury and low concentrations of both arsenic and barium. (c) High concentrations of any two of the chemicals and low concentration of the third. (d) A high concentration of any one of the chemicals and low concentrations of the other two.