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2009 AMC 10B Problem 3

Problem 3 of 25EasierAlgebra

Paula the painter had just enough paint for 3030 identically sized rooms. Unfortunately, on the way to work, three cans of paint fell off her truck, so she had only enough paint for 2525 rooms. How many cans of paint did she use for the 2525 rooms?

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Solution

The lost 33 cans would have painted 3025=530-25=5 rooms, so each room takes 35\dfrac35 of a can. For 2525 rooms she used 3525=15\dfrac35\cdot25=15 cans. Thus, the correct answer is C.

More practice

Concepts: ratio and proportion · rate

Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.