Final answer:
The most practical and efficient way to find the approximate average age of all students taking online coursework is to use sampling.
Step-by-step explanation:
When trying to find the approximate average age of all students taking online coursework, the most practical and efficient way to collect the data would be to use sampling. Sampling involves selecting a small group of individuals from the larger population and collecting data from that group. In this case, you could randomly select a sample of students taking online coursework and gather their ages. By analyzing the ages of the students in the sample, you can estimate the average age of all students taking online coursework.