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385. For how many integers n is 2 的 n 次方=n 的2次方?
(A)None
(B)1
(C)2
(D)3
(E)More than 3
A):C
394. Right traingle PQR is to be constructed in the xy-plane so that the right angle is at P and PR is parallel to the x-axis. The x- and y-coordinates of P, Q, and R are to be integers that satisfy the inequalities -4≦x≦5 and 6≦y≦16. How many different triangles with these properties could be constructed?
(A)110
(B)1,100
(C)9,900
(D)10,000
(E)12,100
A):C
404. A square countertop has a square tile inlay in the center, leaving an untiled strip of uniform width around the tile. If the ratio of the tiled area to the untiled area is 25 to 39, which of the following could be the width, in inches, of the strip?
I. 1 又1/2
II. 3
III.4 又1/2
(A)I only
(B)II only
(C)I and II only
(D)I and III only
(E)I, II, and III
A):E
416. If a certain sample of data has a mean of 20.0 and a standar deviation of 3.0, which of the following values is more than 2.5 standard deviations from the mean?
(A)12.0
(B)13.5
(C)17.0
(D)23.5
(E)26.5
A):A
417.Which of the following is the least positive integer that is divisible by 2,3,4,5,6,7,8,and 9?
(A)15,120
(B)3,024
(C)2,520
(D)1,890
(E)1,680
A):C