For all integer values of a and b such that a > 0 and b<0, which of the following must also be an integer?

(F) 3^{a+b}

(G) 3^{a-b}

(H) 3^{ab}

(J) 3^{-a}

(K)

For all a ≠ 0 and b ≠ 0,

（A） （B） （C） （D） （E）

**Correct Answer: D**

Amy's best marathon time decreased by 10% from 2005 to 2006 and by 20% from 2006 to 2007. By what percent did her best marathon time decrease from 2005 to 2007?

（A）28% （B） 30% （C） 50% （D） 72% （E） 10%

**Correct Answer: A**

Rectangle ABCD lies in the standard (x,y) coordinate plane with corners at A(4,2), B(6,-1), C(1,-4), and D(-1,-1), and is represented by the 2 × 4 matrix . ABCD is then translated, with the corners of the translated rectangle represented by the matrix . What is the value of n?

(A) 0 (B) -1 (C) -2 (D) -3 (E) -4

**Correct Answer: A**

### More ACT Math Exam Questions

- 1As shown in the figure below, what is the sine of angle C?
- 2Which real number satisfies (3
^{x})(9) = 27^{2}? - 3
The measure of the sum of the interior angles of a regular

*n*-sided polygon is (*n*- 2)180°. A regular octagon is shown below. What is the measure of the designated angle? - 4In the figure shown below, bisects BAD, and bisects CAE What is the measure of CAD?
- 5In the figure below, AC is the diameter of the circle, B is a point on the circle, AB is congruent to BC, and D is the midpoint of AC. What is the degree measure of angle ABD?