7. Arrange 7 $3 \times 4$ rectangles without overlapping to form a larger rectangle. The minimum perimeter of this larger rectangle is ( ).
(A) 25
(B) 31
(C) 50
(D) 62
(E) None of the above answers is correct
7. (E) There are three ways to arrange these 7 rectangles into a larger rectangle. Two obvious ways result in rectangles with perimeters of 50 and 62. The method we use is to arrange 4 rectangles into a $4 \times 12$ and 3 rectangles into a $3 \times 12$, thus forming a $7 \times 12$ rectangle, which has a perimeter of 38.