Final answer:
Without additional details about the library's layout and the position of the victims, it is impossible to determine the distance from the back of the library. Hence, the answer is 'Cannot be determined'.
Step-by-step explanation:
To determine the distance of the victims from the back of the library, the question lacks specific details. We would need information about the library's layout, the position of the victims, and possible obstacles or measurement points. Hence, with the information provided in this scenario, it cannot be stated whether the distance is less than 10ft, exactly 10ft, or more than 10ft. Therefore, the answer is: 4) Cannot be determined.
For calculating how many books can be stacked with each book overhanging the one below by 1 inch, the students need to know additional information such as the length of the books, the friction between the books, and potentially the center of mass of the stack. However, this specific piece of information is not available in the question, implying that the necessary details to perform the calculation are not provided.