If the cenus was taken according to the instructions provided to the enumerator, your aunt may have been born in Nov. 1909.

The age was supposed to be as of April 15, 1910. (see reference below...I think it is accurate. I haven't had a chance to research other resources to confirm, but it may be worth looking into)

from: http://usa.ipums.org/usa/voliii/inst1910.shtml

"112. Ages of children.—Take particular pains to get the exact ages of children. In the case of a child not 2 years old, the age should be given in completed months, expressed as twelfths of a year. Thus the age of a child 3 months old should be entered as 3/12, a child 7 months old as 7/12, a child 1 year and 3 months as 1 3/12, etc. If a child is not yet a month old, enter the age as 0/12. But note again that this question should be answered with reference to April 15. For instance, a child who is just a year old on the 17th of April, 1910, should nevertheless be returned as 11/12, because that is the age in completed months on April 15. "