Practice Test 2 - ACT Math

20 questions. Answer them in any order, then submit to see your score and every explanation.

  1. What is f(0)f(0) for the piecewise function f(x)={2x−5if x<−1x2+1if x≥−1f(x) = \begin{cases} 2x - 5 & \text{if } x < -1 \\ x^2 + 1 & \text{if } x \geq -1 \end{cases}?
  2. The function B=800−5nB = 800 - 5n models the number of books in a library, where BB is the number of books and nn is the number of days books are borrowed. How many books are left after 50 days?
  3. A circle has area 16π16\pi. What is the radius of the circle?
  4. In a 4545-4545-9090 right triangle, the hypotenuse has length 10210\sqrt{2}. What is the length of each leg?
  5. How many ways can 2 people be chosen from a group of 8 to serve as a captain and co-captain?
  6. What is the magnitude of vector v\mathbf{v} if v=⟨3,4⟩\mathbf{v} = \langle 3, 4 \rangle?
  7. Which expression is equivalent to 2(a+3)+4a2(a + 3) + 4a? Give your answer in simplest form.
  8. A student tracks the temperature (in °C) of a cooling liquid, which changes linearly with time. The line passes through points (0,18)(0,18) and (4,6)(4,6). What is the y-intercept of the line through these points?
  9. What is the least common multiple (LCM) of 9 and 12?
  10. A classroom has a ratio of students wearing sneakers to students not wearing sneakers of 7:37:3. If 21 students are wearing sneakers, how many students are not wearing sneakers?
  11. Consider the system of equations below: 3x+2y=123x + 2y = 12 and y=x−4y = x - 4. What is the value of x+yx + y for the solution to this system?
  12. A club has 8 members. How many different ways can the club choose a president, vice-president, and secretary?
  13. A polynomial step requires multiplying complex numbers and simplifying. What is (−6+2i)(−1−3i)(-6+2i)(-1-3i)? Use FOIL and apply i2=−1i^2=-1 to write a+bia+bi.
  14. A company uses the polynomial p(x)=−3x3+2x−8p(x) = -3x^3 + 2x - 8 to model a cost. What is the leading coefficient of p(x)p(x)?
  15. A savings plan applies a rule f(x)f(x) to the number of weeks xx you have saved. For the piecewise function f(x)={6−xif x<42x+1if 4≤x<9x2−10if x≥9f(x)=\begin{cases}6-x & \text{if } x<4\\ 2x+1 & \text{if } 4\le x<9\\ x^2-10 & \text{if } x\ge 9\end{cases} what is f(9)f(9)?
  16. A cube-shaped box has side length 7 units. Each face is a square with side 7 units. What is the surface area of the cube in square units?​
  17. A sphere has a diameter of 10 units. What is the surface area of the sphere?
  18. If 6 oranges cost $3, what is the cost of 9 oranges?
  19. A bicycle costs $200. If there is a 10% discount, what is the sale price of the bicycle?
  20. In an AC circuit calculation, a voltage is modeled by the complex number 3+4i3+4i and a current is modeled by 2−5i2-5i. What is (3+4i)+(2−5i)(3+4i)+(2-5i) expressed in standard form a+bia+bi?

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