Three witches (Rosalind, Sabrina and Theresa) are having a duel
between themselves. Rosalind is the most accurate, hitting her target
The witches take it in turns to fire shots. Once a witch has been shot, she can no longer fire shots. To make it fair given their respective accuracies, they agree that the order will be Theresa, Sabrina and Rosalind, and then repeat in that order until the end.
Why is Theresa’s best strategy to fire her first shot away from both of her opponents?