Final answer:
When performing CPR on an infant, the chest should be compressed at least 5 cm deep. The compression should be done with the flat portion of one hand on the sternum in the area between the T4 and T9 line. The emphasis is on performing high-quality chest compressions at a rate of 100 compressions per minute.
Step-by-step explanation:
An infant's chest should be compressed at least 5 cm deep when administering CPR. The compression should be applied to the sternum between the T4 and T9 lines using the flat part of one hand. The focus is on delivering superior chest compressions at a speed of one hundred per minute.