Final answer:
The pulse oximeter should be placed on the hand, foot, or wrist for an infant, and on the finger, hand, foot, or earlobe for an older child.
Step-by-step explanation:
For an infant, the pulse oximeter should be placed on the hand, foot, or wrist. The placement depends on the size and condition of the infant. It should be secured with adhesive tape to ensure proper contact.
For an older child, the pulse oximeter is typically placed on the finger, just like in adults. However, if the child's fingers are too small or the device doesn't fit properly, it can be placed on the hand, foot, or earlobe.