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2005 AMC 12B Problems/Problem 2

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The following problem is from both the 2005 AMC 12B #2 and 2005 AMC 10B #2, so both problems redirect to this page.

Problem

A positive number x has the property that x\% of x is 4. What is x?

\mathrm{(A)}\ 2      \qquad\mathrm{(B)}\ 4      \qquad\mathrm{(C)}\ 10      \qquad\mathrm{(D)}\ 20      \qquad\mathrm{(E)}\ 4...

Solution

0.01x \cdot x=4 \Rightarrow x^2 = 400 \Rightarrow x = \boxed{20}.

See also

2005 AMC 10B (ProblemsResources)
Preceded by
Problem 1
Followed by
Problem 3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
2005 AMC 12B (ProblemsResources)
Preceded by
Problem 1
Followed by
Problem 3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
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