Multiple choice

A delivery vehicle traveled half of a route at 60 mph and then increased its speed for the second half. If the total time for the route was 5 hours, what was the delivery vehicle's average speed during the second half? (1) The total distance of the route was 360 miles. (2) The delivery vehicle's average speed over the entire route was 72 mph.

  1. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

  2. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

  3. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

  4. EACH statement ALONE is sufficient.

  5. Statements (1) and (2) TOGETHER are NOT sufficient.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let total distance be 2D. Average speed = Total Distance / Total Time. (1) D = 180 miles. Time 1 = 180/60 = 3 hours. Time 2 = 5 - 3 = 2 hours. Speed 2 = 180/2 = 90 mph. Sufficient. (2) Avg speed = 72 mph. Total distance = 72 * 5 = 360 miles. D = 180. Time 1 = 180/60 = 3 hours. Time 2 = 2 hours. Speed 2 = 90 mph. Sufficient.

AI explanation

Statement one gives a total distance of 360 miles, meaning each half is 180 miles, so the time taken for the first half at 60 mph is 3 hours. This leaves 2 hours for the second half, meaning the required speed is 180 miles divided by 2 hours, which is 90 mph. Statement two gives an overall average speed of 72 mph for the 5 hour trip, resulting in a total distance of 360 miles, which provides the exact same mathematical conditions and also yields a speed of 90 mph. The value can be found using either statement independently.

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