The owner of a gas station records the number of gallons of gas he sells over a period of time. He notices that the number of gallons of gas he sells depends linearly on the price he charges for each gallon. When he charges $1.77 per gallon of gas he sells 1000 gallons of gas each day. When he charges $2.32 per gallon he sells 400 gallons. How many gallons of gas would the owner sell if he charged $2.19 per gallon? (Round to the nearest whole number.)
A) 1314
B) 2389
C) 876
D) 2190
E) 542

Question

Quizplus · Accepted Answer

The relationship is linear, so we can use the two points (1.77, 1000) and (2.32, 400) to find the equation of the line. The slope is (400 - 1000) / (2.32 - 1.77) = -600 / 0.55 = -1090.91. Using point-slope form, y - 1000 = -1090.91(x - 1.77). Solving for y when x = 2.19 gives approximately 542 gallons.

The Owner of a Gas Station Records the Number of Gallons