Bunuel wrote:
Sheldon left his house at 8:30 a.m. and drove to his friend's house, arriving later that morning at 11:30 a.m. How many kilometers did he drive?
(1) He stopped twice along the way.
(2) His average speed while he was driving was 96 kilometers per hour.
We know that the total time = 3 hours, and we need to answer the question:
total distance = ?
Statement One Alone:=> He stopped twice along the way.
Since he stopped twice, he spent less than 3 hours driving. Without any information related to his speed, we can’t answer the question.
Statement one is not sufficient. Eliminate answer choices A and D.
Statement Two Alone:=> His average speed while he was driving was 96 kilometers per hour.
“While he was driving” is a clue that he might not have been driving continuously during his journey. If driving time ≠ journey time, then average driving speed ≠ average journey speed.
Although we know that journey time = 3 hours and average driving speed = 96 kmph, we still can’t determine the total distance, which would be equal to either (average journey speed)(journey time) or (average driving speed)(driving time).
Statement two is not sufficient. Eliminate answer choice B.
Statements One and Two Together:Since driving time < 3 hours, we have:
(average driving speed)(driving time) < (96 kmph)(3 hours)
total distance < 288 km
Without more information, we can’t answer the question.
The two statements together are not sufficient.
Answer: E