A coin is tossed twice in succession.
a. (i) List the complete sample space for this experiment.
b. (ii) The event E is "getting at least one head". Without calculating its probability, decide whether E is certain, impossible, or neither. Justify your answer.
c. (iii) Rewrite the description of event E so that it becomes
(a) a certain event, and
(b) an impossible event,
while keeping the same random experiment of tossing the coin twice. Explain your reasoning in each case.