请选出正确答案，共10题，每题10分，满分100分：

1. A number’s prime factors are 2, 5, 7, 13and 31. Which of the following must be a factor of the number?

A) 4

B) 6

C) 10

D) 15

E) 25

2. 2.If a + b = 0, then |a| = |b|.
If a and b are real numbers, which of the following can be inferred from the statement above?

A) If |a| = |b|, then a + b = 0.

B) If |a| ≠ |b|, then a + b ≠ 0.

C) If a + b ≠ 0, then |a| ≠ |b|

D) If a - b ≠ 0, then |a| ≠ |b|

E) If |a| ≠ |b|, then a - b = 0.

3. 3.A = {-10, -5, -3, -1, 0, 1, 3, 5, 10}
The elements of Set A, shown above, are multiplied by 2 to get Set B. Which of the following is true about Set B?

A) The mean of B is greater than the mean of A.

B) The median of B is greater than the median of A.

C) The median of B is less than the median of A.

D) The standard deviation of B is equal to the standard deviation of A.

E) The standard deviation of B is exactly twice the standard deviation of A.

4. If matrix A has dimensions 2 by 7 and matrix B has dimensions 7 by 5, what are the dimensions of the product matrix BA?

A) 2 by 2

B) 2 by 5

C) 5 by 2

D) 7 by 7

E) The product BA does not exist.

5. What is the surface area of the cube inscribed in a sphere with the radius of 8?

A) 85.3

B) 512.0

C) 768.0

D) 788.3

E) 804.3

6. The parametric equations x = cos(2t) + 1 and y = 3sin(t) + 2 correspond to a subset of the graph

A) (x−1)21+(y−2)29=1

B) (x−1)21−(y−2)29=1

C) x−2=29(y−2)2

D) x−2=−29(y−2)2

E) x−2=−23(y−2)

7. 20cis(19π18)5cis(2π9)=

A) −23+2i

B) −23−2i

C) 23+2i

D) −2+2i3

E) 2−2i3

8.

A) -5

B) 5

C) 24

D) -∞

E) ∞

9. If 3x−4y+2z=33，2x−8y−1z=−8，4x−6y−3z=11
Then 1x−y+z=

A) 2/25

B) 30/31

C) 31/30

D) 19/2

E) 25/2

10. The slope of the line normal to the graph of y=2ln(sec x) at x=π4 is

A) -2

B) -1/2

C) 1/2

D) 2

E) DNE

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