Final answer:
Determining the range of ages to acquire a certain skill helps establish general guidelines based on average ages of reaching developmental milestones.
Step-by-step explanation:
The purpose of determining the range of ages to acquire a certain skill is to gain a better understanding of when most children reach specific developmental milestones. It is not to determine the exact age at which a child should acquire the skill, but rather to establish a general guideline based on average ages. For example, if most children achieve a certain milestone between the ages of 5 and 9 months, then it can be considered normal for a child to reach that milestone within that range of ages.