A motorist, in a desert 5 km from point A, which is the nearest point on a long straight road, wishes to get to point B on the road. If the car can travel 30 km/ hr and 80 km/hr on the road, find the point where the motorist must meet the road to get to point B in the shortest possible time if point B is 5 km from point A. Use calculus to find your answer.
Calculus is used to solve a rate-of-change word probem. The solution is detailed and well presented. The response received a rating of "5" from the student who originally posted the question.