1988 AMC 8 Problem 13 — Solution | LIVE by Po-Shen Loh

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1988 AMC 8 Problem 13

Below is the professionally curated solution for Problem 13 of the 1988 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1988 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:circumference estimation

Difficulty rating: 860

13.

If rose bushes are spaced about $1$ foot apart, approximately how many bushes are needed to surround a circular patio whose radius is $12$ feet?

$12$

$38$

$48$

$75$

$450$

Solution:

The bushes surround the circular edge, so their number is about the circumference $2\pi r = 2\pi(12).$

Using $\pi \approx 3.14,$ this is about $2 \times 3.14 \times 12 \approx 75$ feet, so roughly $75$ bushes are needed.

Thus, the correct answer is D .

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