Joy is winding balls of yarn for her cat to play with. The first ball is half the size of the second ball. The third ball is three times as large as the first ball. She used 27 feet of yarn for the third ball. How many feet of yarn did she use for the second ball?
The first ball is a third of the size of the third ball, so it used 27 / 3 = <<27/3=9>>9 feet of yarn.
The second ball is twice the size of the first ball, so she used 9 * 2 = <<9*2=18>>18 feet of yarn.
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