A delivery truck must travel from point P to point Q
MATHEMATICS · Single correct · AP · Calculus AB · Analytical Applications of Differentiation · Analytical Applications of Differentiation
Problem
A delivery truck must travel from point P to point Q. Point Q is 6 km north of a straight east–west highway and 12 km east of P. The truck can drive on the highway at 60 km/h and can cross the open field at 40 km/h. If the driver leaves the highway after traveling x kilometers east from P and then heads straight across the field to Q, which value of x (to the nearest tenth of a kilometer) minimizes the time required for the trip?
(a) 8.0 km
(b) 6.6 km
(c) 9.9 km
(d) 4.0 km