AMC 8 2018 Problem 6
AMC8 2018 年第 6 题
行程问题★★☆☆☆
On a trip to the beach, Anh traveled 50 miles on the highway and 10 miles on a coastal access road. He drove three times as fast on the highway as on the coastal road. If Anh spent 30 minutes driving on the coastal road, how many minutes did his entire trip take?
在去海滩的路上，Anh 先在高速上开了 50 英里，然后在沿海通道上开了 10 英里。他在高速上的开车速度是在沿海通道上的 3 倍。若 Anh 在沿海通道上开了 30 分钟，那么他全程开了多少分钟？
- A.50
- B.70
- C.80
- D.90
- E.100
正确答案 · Correct Answer
C
解析 · Solution
Solution 1
Since Anh spends half an hour to drive 10 miles on the coastal road, his speed is 𝑟 = 𝑑 𝑡 = 10 0.5 = 20 mph. His speed on the highway then is 60 mph. He drives 50 miles, so he drives for 5 6 hours, which is equal to 50 minutes (Note that 60 miles per hour is the same as 1 mile per minute). The total amount of minutes spent on his trip is 30 + 50 ⟹ (C) 80.
Since Anh drives 3 times as fast on the highway, it takes him 1 3 of the time to drive 10 miles on the highway than on the coastal road. 1 3 of 30 is 10, and since he drives 50 miles on the highway, we multiply 10 by 5 to get 50. This means it took him 50 minutes to drive on the highway, and if we add the 30 minutes it took for him to drive on the coastal road, we would get (C) 80. -UnstoppableGoddess (helped by qkddud)
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