4. \(\begin{array} { l l l l l l l l l } 23 & 18 & 27 & 9 & 25 & 10 & 12 & 30 & 24 \end{array}\) The numbers in the list represent the weights, in kilograms, of nine suitcases. The suitcases are to be transported in containers that will each hold a maximum weight of 45 kilograms.

1. Calculate a lower bound for the number of containers that will be needed to transport the suitcases.
2. Use the first-fit bin packing algorithm to allocate the suitcases to the containers.
3. Using the list provided, carry out a bubble sort to produce a list of the weights in descending order. You need only give the state of the list after each complete pass.
4. Use the first-fit decreasing bin packing algorithm to allocate the suitcases to the containers.
5. Explain why it is not possible to transport the suitcases using fewer containers than the number used in (d).