Multiple choice

George went on a round trip from New Jersey to New York. While going from New Jersey to New York, he drove at an average speed of 70 miles per hour. He started his journey back on the same route, and due to rush hours his speed was slow. What was the average speed of George during his entire round trip? (1) It took one and a half hours for George to travel from New Jersey to New York. (2) While going from New York to New Jersey, he drove at a constant speed of 49 miles per hour.

  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
B Correct answer
Explanation

Average speed for a round trip is 2 * v1 * v2 / (v1 + v2). Statement 1 gives time but not return speed, so it is insufficient. Statement 2 provides the return speed (49 mph), which allows calculation of the average speed using the formula, making it sufficient.

AI explanation

To find the average speed for the entire round trip, we use the formula 2 times speed one times speed two divided by the sum of speed one and speed two. Statement 2 provides the return speed as 49 miles per hour, which when paired with the given going speed of 70 miles per hour, results in an average speed of 2 times 70 times 49 divided by 119, making it sufficient. Statement 1 only gives the time taken for the first half and does not provide the return speed or distance. Therefore, statement 2 alone is sufficient.

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