Final answer:
Without specific details or regulations regarding the maintenance schedule of LPU-10P life preservers, it is not possible to accurately determine how many out of 100 would require a functional test. Maintenance criteria can include various factors like time intervals, usage, or even random sampling.
Step-by-step explanation:
The question asked does not provide enough specific information to determine how many LPU-10P life preservers out of 100 will require a functional test.
Usually, the need for functional testing of equipment such as life preservers is determined by a set of predefined criteria or regulations which could include factors such as time intervals, usage, or random sampling.
For a specific number, you would need to refer to these regulations or the maintenance schedule for the LPU-10P life preservers. It could be a specific percentage or all of them depending on the guidelines set forth for maintaining such safety equipment.