A1. In a convex quadrilateral, the exterior angles are in the ratio $7: 4: 6: 1$. In what ratio are the interior angles of this quadrilateral at the same vertices?
(A) $2: 5: 3: 8$
(B) $8: 3: 5: 2$
(C) $1: 6: 4: 7$
(D) $7: 4: 6: 1$
(E) $11: 14: 12: 17$
A1. We see that the sum of the exterior angles in a convex polygon is $360^{\circ}$. The exterior angles thus measure in sequence $140^{\circ}, 80^{\circ}, 120^{\circ}$ and $20^{\circ}$. The interior angles are therefore in the ratio $40^{\circ}: 100^{\circ}: 60^{\circ}: 160^{\circ}$. Simplifying the ratio, we get $2: 5: 3: 8$.