2012 AMC 12B Problem 3

Below is the professionally curated solution for Problem 3 of the 2012 AMC 12B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2012 AMC 12B solutions, or check the answer key.

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Concepts:linear equation

Difficulty rating: 860

For a science project, Sammy observed a chipmunk and a squirrel stashing acorns in holes. The chipmunk hid $3$ acorns in each of the holes it dug. The squirrel hid $4$ acorns in each of the holes it dug. They each hid the same number of acorns, although the squirrel needed $4$ fewer holes. How many acorns did the chipmunk hide?

$30$

$36$

$42$

$48$

$54$

Solution:

Let $h$ be the number of holes the chipmunk dug. The chipmunk hid $3h$ acorns and the squirrel hid $4(h-4)$ acorns.

Since they hid the same number, $3h=4(h-4),$ which gives $h=16.$

The chipmunk hid $3\cdot16=48$ acorns.

Thus, the correct answer is D.

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