A car being used for a trip to the Geyser starts with 15 gallons, a full tank, of gasoline. The car gets 25 miles per gallon orone-twenty-fifth 1 25of a gallon per mile.
The equation that represents this situation is y = -one-twenty-fifth 1 25 x + 15 where y represents the gasoline in the gas tank and x represents the miles used per gallon of gasoline.
Answer the following questions in your notes.
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The graph of y = -one-twenty-fifth 1 25 x + 15 is shown at the right.
1. What does the slope represent in this situation?
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2. What does the y- intercept represent in this situation?
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3. Why is the graph sloping downward? Interactive popup. Assistance may be required.
Because the number of gallons in the tank decreases the more miles that are driven.
If you look at the labels on the axes, you will see that the meaning of slope can be found by writing the labels in the rise over run rise run formula.
rise over run rise run = gallons used over miles driven gallons used miles driven , or the gallons used per mile = -one-twenty-fifth 1 25