Final answer:
Using the formula time = distance ÷ speed, with a distance of 100 miles and speed of 45 mph, it takes the bus approximately 2.22 hours or roughly 133 minutes to return from Chicago.
Step-by-step explanation:
To calculate the time it takes for the bus to return from Chicago covering a distance of 100 miles at an average speed of 45 mph, we use the formula time = distance ÷ speed. Plugging in the given values, we get time = 100 miles ÷ 45 mph.
The calculation would give us approximately 2.22 hours, which can be further converted into minutes by multiplying by 60, resulting in approximately 133.33 minutes for the bus to complete the return trip. Since most people don't refer to time in decimal form, it would be more practical to round this to the nearest minute, giving us an answer of roughly 133 minutes for the bus to return.