1985 AMC 8 Problem 5

Attempt Problem 5 of the 1985 AMC 8 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 1985 AMC 8 solutions, or check the answer key.

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5.

The grades in a mathematics class for the last grading period were: 55 students earned an A, 44 earned a B, 33 earned a C, 33 earned a D, and 55 earned an F. If A, B, C, and D are satisfactory grades, what fraction of the grades are satisfactory?

12\dfrac{1}{2}

23\dfrac{2}{3}

34\dfrac{3}{4}

45\dfrac{4}{5}

910\dfrac{9}{10}

Answer: C
Concepts:data and graph interpretationfraction

Difficulty rating: 660

Solution:

The satisfactory grades number 5+4+3+3=15,5 + 4 + 3 + 3 = 15, and the total number of grades is 15+5=20.15 + 5 = 20.

So the fraction that is satisfactory is 1520=34.\dfrac{15}{20} = \dfrac{3}{4}.

Thus, the correct answer is C .

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