1994 AMC 8 Problem 18
Below is the professionally curated solution for Problem 18 of the 1994 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1994 AMC 8 solutions, or check the answer key.
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Difficulty rating: 920
18.
Mike leaves home and drives slowly east through city traffic. When he reaches the highway he drives east more rapidly until he reaches the shopping mall where he stops. He shops at the mall for an hour. Mike returns home by the same route as he came, driving west rapidly along the highway and then slowly through city traffic. Each graph shows the distance from home on the vertical axis versus the time elapsed since leaving home on the horizontal axis. Which graph is the best representation of Mike's trip?
Solution:
On the way out Mike drives slowly (a shallow slope) then rapidly (a steep slope), so the distance rises slowly and then more steeply. During the hour at the mall the distance stays the same, a flat segment.
On the return he drives rapidly (steep) then slowly (shallow), so the distance falls steeply and then levels off. Only the graph with a slow-then-fast rise, a flat top, and a fast-then-slow fall fits.
Thus, the correct answer is B .
Problem 18 in Other Years
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