AMC 8 Daily Practice Round 8
Complete problem set with solutions and individual problem pages
A car travels from City to City . If its speed is increased by , it can arrive one hour earlier than the originally planned time. If it travels kilometers at the original speed and then increases its speed by , it can arrive minutes earlier. What is the distance between City and City in kilometers?
- A.
- B.
- C.
- D.
- E.
When the car’s speed is increased by , the speed ratio is .
For the same distance, the time ratio should be .
Thus, the time to travel the whole distance at the original planned speed is
For the latter part of the trip, when the speed is increased by , the speed ratio is , so the time ratio should be .
Arriving minutes earlier means that at the original planned speed, this part of the trip would take
From this, it is easy to find that the distance between and is
