16. The inside dimensions of a rectangular wooden box are 6 inches by 8 inches by 10 inches. A cylindrical cannister is to be placed inside the box so that it stands upright when the closed box rests on one of its six faces. Of all such cannisters that could be used, what is the radius, in inches, of the one that has maximum volume?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 8
答案:B, 我选C
体积最大=> 半径最大=>R=5
7. In a certain brick wall, each row of bricks above the bottom row contains one less brick than the row just below it. If there are 5 rows in all and a total of 75 bricks in the wall, how many bricks does the bottom row contain ?
(A) 14
(B) 15
(C) 16
(D) 17
(E) 18
答案
题目什么意思啊?并没有讲bottom row 的相对位置?也没说就是中间那个row?
题目在XDF的数学分册PS-section 34-15,图贴不上,题目如下:
15. The shaded region in the figure above represents a rectangular frame with length 18 inches and width 15 inches. The frame encloses a rectangular picture that has the same area as the frame itself. If the length and width of the picture have the same ratio as the length and width of the frame, what is the length of the picture, in inches?
(A) 9 * root 2
(B) 3/2
(C) 9/root 2
(D) 15(1-1/root 2)
(E) 9/2
答案:A
