If three dozen muffins cost $9, what is the cost per muffin?
There are 3 x 12 = <<3*12=36>>36 muffins in three dozens.
Therefore, each muffin costs $9/36 = $<<9/36=0.25>>0.25. Answer: \boxed{0.25}.
Therefore, each muffin costs $9/36 = $<<9/36=0.25>>0.25. Answer: \boxed{0.25}.