During a fractional distillation of a 25mL ethanol/H2O soln, it was found that first the temperature stayed constant at ~75 C for 3mL of soln, then it went up to 100 C for the rest of the soln.

Question

The first question is:
Assuming that the unknown (ethanol) did not form an azeotrope, the beginning percent composition of ethanol/H2O soln would be:

I put: (3/25)*100 = 12% composition

The second question is:
If the unknown (ethanol) DID form an azeotrope w/ water, the beginning percent composition of ethanol/H2O soln would be:

I have no idea how to answer this question.