Answer:
Assuming that the capacity of the new X-ray machine is the same as the capacity of two older machines, the difference results from the number of units waiting in line (queue). You would need two different groups of workers to move the containers into the correct position if you use the two older machines, while you need only one group to move them to the new machine. This decreases lead time since coordinating work also requires time, it might be a short time, but it is more time at the end of the day.