SAT备考数学练习题（7）
- 2017年08月01日14:57 来源：互联网
- 参与（0） 阅读（4083）
SAT是Scholastic Aptitude Test的缩写，是申请几乎所有美国大学必须参加的考试。通常，希望继续接受高等教育的高中生需要参加SAT考试，并且SAT考试得分是获取奖学金的重要标准之一。大部分美国大学要求SAT考试作为录取的条件并根据SAT得分授予奖学金。
A train traveling 60 miles per hour for 1 hour covers the same distance as a train traveling 30 miles per hour for how many hours?
A. 3
B. 2
C. 1
D. 1/2
E. 1/3
Answer: B
When the speed of a train in miles per hour is multiplied by the travel time in hours, the distance traveled by the train is obtained. The distance that the first train travels is 60 miles per hour times 1 hour, which is 60 miles. Using the variable x for the travel time, in hours, of the second train, the distance that the second train travels is 30 miles per hour times x hours, which is 30x miles. Since the two trains travel the same distance, 60 = 30x, which gives x = 2 hours, the travel time of the second train.
设30 miles per hour的火车 需要x小时
于是就有60×1=30x
解之，得到x=2
所以选B
