A school cafeteria has a juice dispenser that holds 640 fluid ounces of juice when completely filled. Juice is offered in two serving sizes: 4 ounces or 8 ounces. Each day approximately 7 out of 10 students choose the 4 ounce serving size and the other students choose the 8 ounce serving size.
Based on this information, estimate the number of servings that can be dispensed from the juice dispenser before it needs to be refilled. Show or explain each step you used when finding your estimate.