Question

A ferry takes several trips between points A and B. It moves at a constant speed of 0.35 miles/minute and takes the same route on each trip. The total duration of a round trip from point A to point B and back is 80 minutes, ignoring the time spent stopped at point B. If d is the ferry’s distance from point A in miles and t is the time in minutes, which equation models the ferry’s distance from point A for the duration of the trip?

Answer 1

D. -|0.35t -14| +14

Explanation:

The problem statement is asking for an expression for distance in miles, so the constants in the expression will be miles. In the time it takes to get to point B (40 minutes), the ferry has gone (0.35 mi/min)×(40 min) = 14 mi. Hence the maximum value of the function must be 14. The only function with that characteristic is the one of selection D.