Explanation:
Suppose that the weight (in pounds) of an airplane is a linear function of the amount of fuel (in gallons) in its tank. When carrying 15 gallons of fuel, the airplane weighs 2187 pounds. When carrying 35 gallons of fuel, it weighs 2303 pounds. How much does the airplane weigh if it is carrying 50 gallons of fuel?
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You have two points relating fuel and weight.
(15,2187) and (35,2303)
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slope = (2303-2187)/(35-15) = 5.8
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intercept = ?
2187 = 5.8*15 + b
b = 2100
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Equation:
f(x) = 5.8x + 2100
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f(50) = 2390 lbs.
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