Samples of size n = 125 is too small in a US census so there is no way to tell how the median will look like. The answer is not enough information provided.
The sum of the measures of the angles of a convex quadrilateral is 360° as a convex quadrilateral is made of two triangles. Yes, this property also holds true for a quadrilateral which is not convex. This is because any quadrilateral can be divided into two triangles.
