Final answer:
In a child, high quality CPR should be started if the heart rate is 100 bpm or lower.
Step-by-step explanation:
The heart rate (HR) in a child of certain age range is considered high quality CPR if it is less than or equal to 100 beats per minute (bpm) or lower. High quality CPR should be started with immediate chest compressions followed by rescue breaths, also known as cardiopulmonary resuscitation. CPR is performed to maintain blood circulation and provide oxygen to the body when the heart is not functioning properly.