The problem asks how far the bus will go in 120 minutes, given that it travels 15 miles in 30 minutes.

Step-by-step solution:

1. Determine the bus's rate of travel:

   • The bus travels 15 miles in 30 minutes.
   • To find the rate of travel, divide the distance by the time:

   $\text{Rate} = \frac{15 \text{ miles}}{30 \text{ minutes}} = 0.5 \text{ miles per minute}$

2. Calculate the distance traveled in 120 minutes:

   • Now that we know the bus travels 0.5 miles per minute, we can multiply that rate by 120 minutes to find the distance for 120 minutes:

   $\text{Distance} = 0.5 \times 120 = 60 \text{ miles}$

Thus, the bus will travel 60 miles in 120 minutes.

The correct answer is: 60 miles.

Would you like further clarification or have any questions about the solution?

Here are some related questions you might find interesting:

1. How do you calculate rate from a distance and time?
2. How would the result change if the bus traveled 10 miles in 30 minutes instead?
3. How do you calculate time if you know distance and rate?
4. What if the bus was traveling at 0.25 miles per minute? How far would it go in 120 minutes?
5. How can you set up a proportion to solve this type of problem?

Tip: Always ensure the units of measurement (miles, minutes) are consistent when performing calculations.