Multiple choice

Marc travels from his home in San Francisco to his office in Las Vegas, covering a total distance of 430 miles. He drives the first 240 miles at a constant speed of 60 miles per hour. For the remaining distance, due to road construction, he drives at a reduced speed of 38 miles per hour. Along the way, he also takes a 30-minute coffee break. What is his approximate average speed for the entire journey, excluding the stoppage time?

  1. 44 miles per hour

  2. 48 miles per hour

  3. 52 miles per hour

  4. 54 miles per hour

  5. 56 miles per hour
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Distance 1 = 240 miles at 60 mph. Time 1 = 240/60 = 4 hours. Distance 2 = 430 - 240 = 190 miles at 38 mph. Time 2 = 190/38 = 5 hours. Total distance = 430 miles. Total time = 4 + 5 = 9 hours. Average speed = 430 / 9 = 47.77 mph, which is approximately 48 mph.

AI explanation

Using the formula time = distance divided by speed, the time for the first part is 240 divided by 60, equaling 4 hours, and the time for the second part is 190 divided by 38, equaling 5 hours. The total travel time excluding the stoppage is 9 hours, and the total distance is 430 miles. Therefore, the average speed for the entire journey is 430 divided by 9, which is approximately 48 miles per hour.

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