2007 AMC 10B Problem 6

Below is the professionally curated solution for Problem 6 of the 2007 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2007 AMC 10B solutions, or check the answer key.

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Concepts:inequalitylinear equation

Difficulty rating: 1120

6.

The 2007 AMC 10 will be scored by awarding 66 points for each correct response, 00 points for each incorrect response, and 1.51.5 points for each problem left unanswered. After looking over the 2525 problems, Sarah has decided to attempt the first 2222 and leave only the last 33 unanswered. How many of the first 2222 problems must she solve correctly in order to score at least 100100 points?

1313

1414

1515

1616

1717

Solution:

The three blank problems give 31.5=4.53\cdot 1.5 = 4.5 points, so Sarah needs 1004.5=95.5100-4.5=95.5 points from the first 22.22.

Since 95.5/695.5/6 lies between 1515 and 16,16, she must answer at least 1616 correctly, which would give a score of 100.5.100.5.

Thus, the correct answer is D.

Problem 6 in Other Years