The answer is 4:1 only if AB = BC. If you divide the triangle in half ABD and DBC share one side, DB, while one side of each triangle, AD & DC, has the same lenght. The ratio of the remaining side of each triangle, AB and BC, can have an infinite number of values. Since you can compute the area of a triangle using the lenght of all three sides the ratio of the area the two triangles must have an infinite number of values, depending of what kind of triangle that is originally used in the question (which is not mentioned here).
Please take note that English is not my native language