Final answer:
To find the average speed of the entire journey, calculate the distance and time for each part separately and then sum them up. Finally, divide the total distance by the total time to find the average speed. In this case, the average speed of the entire journey is approximately 1 mph.
Step-by-step explanation:
To find the average speed of the entire journey, we need to calculate the total distance traveled and the total time taken. For the first part of the journey, the car travels at an average speed of 45 mph for 40 minutes. To find the distance traveled, we can use the formula Distance = Speed × Time, where the speed is 45 mph and the time is 40 minutes (converted to hours by dividing by 60). This gives us a distance of 45 × (40/60) = 30 miles.
Similarly, for the second part of the journey, the car travels at an average speed of 60 mph for 25 minutes. Using the same formula, the distance traveled is 60 × (25/60) = 25 miles.
To find the total distance, we sum up the distances from both parts: 30 + 25 = 55 miles. To find the total time, we sum up the time from both parts: 40 + 25 = 65 minutes (converted to hours by dividing by 60). Now, we can find the average speed by dividing the total distance by the total time: 55/65 ≈ 0.846 mph. Rounding to the nearest whole number, the average speed of the entire journey is 1 mph.