AMC 8 · 2019 · #5

Grade 8 rate-ratioalgebra
rategraph-readingslope-intercept identify-subproblemspattern-recognition ↑ Prerequisites: graph-readingrate
📏 Medium solution 💡 3 insights 📊 Diagram

Problem

A tortoise challenges a hare to a race. The hare eagerly agrees and quickly runs ahead, leaving the slow-moving tortoise behind. Confident that he will win, the hare stops to take a nap. Meanwhile, the tortoise walks at a slow steady pace for the entire race. The hare awakes and runs to the finish line, only to find the tortoise already there. Which of the following graphs matches the description of the race, showing the distance dd traveled by the two animals over time tt from start to finish?

figure

figure

Pick an answer.

(A)
(distance-time graph A) hare and tortoise — variant interpretation
(B)
(distance-time graph B) tortoise straight line; hare steep up, flat (nap), steep up — arrives after tortoise
(C)
(distance-time graph C) variant interpretation
(D)
(distance-time graph D) variant interpretation
(E)
(distance-time graph E) variant interpretation

AMC 8 2019 problem © Mathematical Association of America (MAA AMC). Reproduced for educational use.

Try it yourself first — the explanation is most useful after you’ve attempted it.