What would a Utilitarian do in this case? What would you do and why?

Jim, a botanist travelling in South America, comes upon a public execution in a small town. A military captain has lined up twenty Indians. He explains to Jim that they have been chosen at random from the local population, which has recently been protesting against the government. The captain offers Jim a guest’s privilege. If Jim wishes, he can select one of the Indians and shoot him himself and then the other nineteen will go free. Otherwise, the execution by the captain’s henchman, Pedro, will go ahead as planned.

What would a Utilitarian do in this case? What would you do and why?

(Papers must be 3-4 pages, double-spaced.)