Final answer:
Assuming an average cycling speed of 18 km/h, a student would need approximately 11.67 hours to bike 210 km. This calculation uses the formula T = D / Vavg, and it's an estimate as actual time may vary.
Step-by-step explanation:
To determine how long a student must ride to bike 210 km, we need to know the student's average biking speed. Since the question does not provide this information, we will consider an average cycling speed of 18 km/h, which is typical for a casual cyclist as per the information provided in the reference material.
Given the average speed (Vavg), the time (T) required to travel a certain distance (D) can be calculated using the formula T = D / Vavg. For a distance of 210 km, the calculation would look like this:
T = 210 km / 18 km/h = 11.67 hours
Therefore, if the student cycles at an average speed of 18 km/h, she would need approximately 11.67 hours to bike 210 km.
Note: This is an estimation based on an average speed. Actual time may vary depending on the cyclist's speed, terrain, and other factors such as breaks and weather conditions.