[問題]新pp問題2

[mht]

2. During a trip on an expressway, Don drove a total of X miles. His average speed on a certain 5-mile section of the expressway was 30 miles per hour, and his average speed for the reminder of the trip was 60 miles per hour. His travel time for the X mile trip was what percent greater than it would have been if he has traveled at a constant rate of 60 miles per hour for the entire trip?
Ans. 500/x %

[clbb]

因為後半段的速率都一樣 所以不管

前半段原本的時間是5miles/30 miles per hour

若用時速60 miles 則所花時間=5/60

(5/30-5/60)/(X/60)

=5/X

=500/X %