Final answer:
The question requires calculating the horizontal force to hold a displaced mail bag, but it lacks sufficient information to provide an accurate answer.
Step-by-step explanation:
The question is regarding the horizontal force needed to hold a 900 kg mail bag in its new position when it has been displaced sideways. To find the horizontal force, we need to consider the tension in the rope and the horizontal and vertical components of the forces. However, the question does not provide enough information to calculate the force, namely the original vertical position of the bag or the height it hangs from when displaced. Typically, such a problem could be solved using trigonometric functions and the concept of vectors but key piece of information is missing to accurately solve this problem.