A real estate agent developed a model to relate a house's selling price (Y) to the area of floor space (X) and the area of floor space squared (X²) . The multiple regression equation for this model is: Y = 125 - 3X + X²where: Y = selling price (times $1,000)
X = square feet of floor space (times 100)
What is the difference in selling prices of a house with 1,650 square feet and one with 1,750 square feet?

Question

Quizplus · Accepted Answer

To find the difference in selling prices, calculate Y for both 1,650 and 1,750 square feet and subtract the two results. For 1,650 sq ft (X = 16.5): Y = 125 - 3(16.5) + (16.5)^2 = 125 - 49.5 + 272.25 = 347.75. For 1,750 sq ft (X = 17.5): Y = 125 - 3(17.5) + (17.5)^2 = 125 - 52.5 + 306.25 = 378.75. The difference is 378.75 - 347.75 = 31,000 (times $1,000).

A Real Estate Agent Developed a Model to Relate a House's