Final answer:
The expression for the average cost per minute for a phone usage between 0 and 200 minutes in the provided scenario is 50/x, which represents dividing the total fixed cost by the number of minutes used.
Step-by-step explanation:
The student has asked for the expression that represents the average cost per minute for phone usage between 0 and 200 minutes. To determine this, we need to calculate the total cost of the plan within those minutes and then divide that cost by the number of minutes, x, to find the average cost per minute.
Given that the basic plan is $50 for up to 200 minutes, the total cost does not change if the number of minutes used is between 0 and 200. Therefore, regardless of whether you use 1 minute or 200 minutes, the cost is still $50. To find the average cost per minute, we divide the total cost by the number of minutes, which is x. So, the expression for the average cost per minute when the usage is between 0 and 200 minutes is 50/x.
Thus, the correct answer to the question is a. 50/200, which simplifies to 50/x when considering x minutes of usage where 0 < x ≤ 200.