可汗学院
1.The average price of a certain type of coffee worldwide was $0.51 per pound in 2008. The price per pound increased about $0.18 each year until 2014, and is expected to do so for the next two years. Which of the following graphs represents the relationship between years after 2008, t, and price per pound, P, in dollars, of this coffee worldwide?
2. A farmer observes that the demand for corn Q, in thousands of bushels per month, and price P, in dollars per bushel, are related by a linear function. If a demand of 2,500 bushels per month corresponds to a price of $4.00 per bushel, and a demand of 3,000 bushels per month corresponds to a price of $3.20 per bushel, which of the following graphs represents the relationship between P and Q?
3. The lines f and g are graphed BELOW in the xy-plane. Line g can be written as the equation y=ax+b, where a and b are constants. Which of the following equations represents line f? Please choose from one of the following options.
A. y=ax−b
B. y=−ax+b
C. −y=ax+b
D. x=ay+b
Correct Answer: C Difficult level: 3
5. The equation 6y+12x=18 is graphed in the xy-plane. Which of the following equations has a graph that is perpendicular to the graph of the above equation?
A. y=-2x+3
B. y=(1/2)x+3
C. y=2x+3
D. y=-(1/2)x+3
Correct Answer: B Difficult level: 3
