ECA Review #9

1. ECA Review #9 Relating Slope and y-intercept to a real life application 40% of the test will deal with linear equations and inequalities

2. The equation M=-2t+50 refers to how the money in Tom’s bank account changes with respect to time (M: money, t: time in days). Which of the following statements are true? • On the first day, Tom has no money in his account. • Tom loses $2 every day • Tom gains $50 every day • Tom will not have money in his account after 10 days. [Default] [MC Any] [MC All]

3. The function H(t)=3t+10 refers to how the height of a plant changes with respect to time (H: height in cm, t: time in days). What does the slope indicate?___ cm ___ ___ • 3 cm per day

4. The graph shows how your distance from home has changed based on the minutes you have been traveling. What must be true? • You are getting closer to home the longer you travel • The slope indicates that you are traveling at a constant speed • The y-intercept indicates you started at home • Both B & C are true [Default] [MC Any] [MC All]

5. The graph shows how the height of a rose bush has changed over time. Which statement is true? • The rose bush is decreasing in height • The rose bush starts at 6 ft tall • The slope is 3, which describes how the height of the rose bush has changed over time • The y-intercept is 3 which describes the starting height of the rose bush [Default] [MC Any] [MC All]

6. You are typing a word document that already contains 100 words. You can type at a rate of 20 words per minute. If the y-axis of this situation was total words and the x-axis was time (in minutes), what would the y-intercept be? • 100 • 0

7. A phone company has a monthly cell plan that can be described by the function: 30 + 0.05x where x is the number of minutes over 500. Which statement is true? • The cell phone costs $30 per month regardless of how many minutes a customer uses. • The phone company charges a $30 fine for using the phone for more than 500 minutes. • The phone company charges 5 cents per minute for every minute used during the month. • The phone only costs $30 if the customer uses the phone for less than 500 minutes [Default] [MC Any] [MC All]

8. If “number of years working at a company” is plotted on the x-axis, and “number of vacation days allowed” is plotted on the y-axis, which statement is FALSE? • The company gives every employee at least 5 days of vacation. • After working at the company for 5 years, you will be allowed 15 days of vacation. • The y-intercept is 0. • The rate of change in the graph is constant. [Default] [MC Any] [MC All]

9. The function T(x) = 20x + 80 describes how the temperature of an oven changes with respect to time (T is temperature, x is time in minutes). What does the y-intercept tell you about the oven? • The temperature changes at a rate of 20 degrees per minute • The temperature starts at 20 degrees • The temperature changes at a rate of 80 degrees per minute • The temperature starts at 80 degrees [Default] [MC Any] [MC All]

10. The function T(x) = 20x + 80 describes how the temperature of an oven changes with respect to time (T is temperature, x is time in minutes). What does the slope tell you about the oven? • The temperature changes at a rate of 20 degrees per minute • The temperature starts at 20 degrees • The temperature changes at a rate of 80 degrees per minute • The temperature starts at 80 degrees [Default] [MC Any] [MC All]

11. The function H(t) = 3t + 10 refers to how the height of a plant changes with respect to time (H is height in centimeters, t is time in days). If height is plotted along the y-axis, where would the line of the equation cross the y-axis? • 10 • 0