2016 AMC 8 Problem 16

Below is the video solution and professionally curated solution for Problem 16 of the 2016 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2016 AMC 8 solutions, or check the answer key.

All of the real AMC 8, AMC 10, AMC 12, and AIME problems in our complete solution collection are used with official legal permission of the Mathematical Association of America (MAA).

Concepts:relative speeddistance rate and timeratio and proportion

Difficulty rating: 1240

16.

Annie and Bonnie are running laps around a 400400-meter oval track. They started together, but Annie has pulled ahead, because she runs 25%25\% faster than Bonnie. How many laps will Annie have run when she first passes Bonnie?

114 1\dfrac{1}{4}

313 3\dfrac{1}{3}

4 4

5 5

25 25

Video solution:
Solution video thumbnail
Play video

Click to load, then click again to play

Written solution:

Since Annie is 25%25\% faster than Bonnie, for every lap Bonnie finishes, Annie completes 1141 \dfrac{1}{4} laps. Therefore, Annie gains a quarter lap every time Bonnie finishes a lap.

With this in mind, for Annie to completely lap Bonnie, Bonnie must finish 44 laps, which means that Annie finished 55 laps.

Thus, D is the correct answer.

Problem 16 in Other Years

1985 AMC 8 · 1986 AMC 8 · 1987 AMC 8 · 1988 AMC 8 · 1989 AMC 8 · 1990 AMC 8 · 1991 AMC 8 · 1992 AMC 8 · 1993 AMC 8 · 1994 AMC 8 · 1995 AMC 8 · 1996 AMC 8 · 1997 AMC 8 · 1998 AMC 8 · 1999 AMC 8 · 2000 AMC 8 · 2001 AMC 8 · 2002 AMC 8 · 2003 AMC 8 · 2004 AMC 8 · 2005 AMC 8 · 2006 AMC 8 · 2007 AMC 8 · 2008 AMC 8 · 2009 AMC 8 · 2010 AMC 8 · 2011 AMC 8 · 2012 AMC 8 · 2013 AMC 8 · 2014 AMC 8 · 2015 AMC 8 · 2017 AMC 8 · 2018 AMC 8 · 2019 AMC 8 · 2020 AMC 8 · 2022 AMC 8 · 2023 AMC 8 · 2024 AMC 8 · 2025 AMC 8 · 2026 AMC 8