Final answer:
To find the driving speed for 200 miles traveled in 2.5 hours, we use the formula for average speed, which is distance divided by time. The formula shows an average speed of 80 miles per hour. The provided option (4) is the correct formula, reaffirming that the calculated average speed is reasonable.
Step-by-step explanation:
To determine how fast you were driving when you traveled 200 miles in 2.5 hours, you need to calculate the average speed, which is the distance traveled divided by the time it took to travel that distance. In this case, average speed (r) is given by the formula r = distance ÷ time. Using the values given:
r = 200 miles ÷ 2.5 hours = 80 miles per hour.
This means that you were driving at an average speed of 80 miles per hour.
Let's consider the option (4) provided in the question: 200 = r × 2.5. This is the correct formula to use when you want to find out the rate because it is derived from the basic formula for speed which is speed = distance ÷ time. By rearranging this formula, we can isolate 'r' to find the rate, and it becomes r = distance ÷ time, which properly calculates the average speed.
Lastly, we check if the answer is reasonable. If you were to travel at 80 miles per hour, in 2.5 hours you would cover 200 miles, which confirms that our calculation is correct.