In testing the lethal concentration of a chemical found in polluted water. it is found that a certain concentration will kill 20
% of the fish that are subjected to it for 24 hours. if 20 fish are placed in a tank containing this concentration of chemical. find the probability that after 24 hours :______a) Exactly 14 fish survive ? b) at least 10 survive ? c) at most 16 fish will die ?