A train travels from New York City to Chicago. a distance of approximately 840 miles, at an average rate of 60 miles per hour and arrives in Chicago at 6:00 in the evening, Chicageo time.At what hour in the morning, New York City time, did the train depart for Chicago? (Note: Chieago time is one hour earlier than New York City time.)
The train arrives ar Chicago at 18:00 Chicago time, and the train drives 840/60=14hours. That means, the train depart at NY at 18-14=4:00 Chicago time. 4:00 Chicago time =>5:00 NY time. 其实从地理角度,Chicago是晚NY一个小时的,正因为晚,它在时间上才是earlier (4点比起5点是earlier嘛)。