1986 AMC 8 Problem 11 — Solution | LIVE by Po-Shen Loh

LIVE

English

1986 AMC 8 Problem 11

Attempt Problem 11 of the 1986 AMC 8 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1986 AMC 8 solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

11.

If $A * B$ means $\dfrac{A + B}{2},$ then $(3 * 5) * 8$ is

$6$

$8$

$12$

$16$

$30$

Answer: A

Concepts:custom operation

Difficulty rating: 820

Solution:

First, $3 * 5 = \dfrac{3 + 5}{2} = 4.$ Then $4 * 8 = \dfrac{4 + 8}{2} = 6.$

Thus, the correct answer is A .

← Problem 10#10 Full Exam Problem 12#12 →

Problem 11 in Other Years

1985 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 · 2016 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