1993 AMC 8 Problem 21 — Solution | LIVE by Po-Shen Loh

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1993 AMC 8 Problem 21

Below is the professionally curated solution for Problem 21 of the 1993 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1993 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:percentage

Difficulty rating: 820

21.

If the length of a rectangle is increased by $20\%$ and its width is increased by $50\%,$ then the area is increased by

$10\%$

$30\%$

$70\%$

$80\%$

$100\%$

Solution:

The new length is $1.2$ times the old and the new width is $1.5$ times the old, so the new area is $1.2 \times 1.5 = 1.8$ times the old area.

That is an increase of $80\%.$

Thus, the correct answer is D .

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