2020 AMC 12A Problem 1

Attempt Problem 1 of the 2020 AMC 12A 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 2020 AMC 12A solutions, or check the answer key.

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1.

Carlos took 70%70\% of a whole pie. Maria took one third of the remainder. What portion of the whole pie was left?

10%10\%

15%15\%

20%20\%

30%30\%

35%35\%

Answer: C
Concepts:percentagefraction
Difficulty rating: 840
Solution:

After Carlos takes 70%,70\%, the remaining portion is 30%.30\%.

Maria takes one third of this, namely 1330%=10%,\tfrac13 \cdot 30\% = 10\%, leaving 30%10%=20%.30\% - 10\% = 20\%.

Thus, C is the correct answer.

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