Multiple choice

George traveled from Nashville to Cookville at the speed of 70 miles per hour. Due to heavy traffic, he reduced the speed to 50% and drove from Cookville to Knoxville at this reduced speed. If the distance between Cookville and Knoxville was three times the distance between Nashville and Cookville, what was George's average speed for the entire trip?

  1. 50 miles per hour

  2. 45 miles per hour

  3. 40 miles per hour

  4. 37.5 miles per hour

  5. 35 miles per hour
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let distance Nashville-Cookville = d. Then Cookville-Knoxville = 3d. Speed 1 = 70 mph. Speed 2 = 35 mph. Time 1 = d/70. Time 2 = 3d/35 = 6d/70. Total distance = 4d. Total time = 7d/70 = d/10. Average speed = 4d / (d/10) = 40 mph.

AI explanation

Assume the distance from Nashville to Cookville is D, making the distance from Cookville to Knoxville 3D, for a total distance of 4D. The reduced speed is 50% of 70 mph, which is 35 mph. The total time for the trip is D divided by 70 plus 3D divided by 35, which equals D divided by 70 plus 6D divided by 70, resulting in 7D divided by 70 or D divided by 10. The average speed is total distance divided by total time, so 4D divided by (D divided by 10) equals 40 miles per hour.

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