A quadratic trend equation was estimated from monthly sales of trucks in the United States from July 2006 to July 2011.The estimated trend y_t = 106 + 1.03t + 0.048t² where y_t units are in thousands.From this trend,how many trucks would be sold in July 2012? A) About 308,419 B) About 524,889 C) About 436,982 D) About 223,831

Question

Quizplus · Accepted Answer

To find the number of trucks sold in July 2012, we need to substitute t=72 in the trend equation and solve for y. 
y = 106 + 1.03(72) + 0.048(72^2) 
y = 106 + 74.16 + 248.83 
y ≈ 429.99 thousand or about 436,982 trucks. Therefore, the best choice is C.

A Quadratic Trend Equation Was Estimated from Monthly Sales of Trucks