Final answer:
The distance d as a function of time t for a pedestrian walking at a speed of 3 km/h is expressed as d(t) = 3 × t, which indicates that the pedestrian walks 3 kilometers for every hour of walking.
Step-by-step explanation:
The distance d that a pedestrian walks is a function of time t when walking at a constant speed. If a pedestrian is walking at a speed of 3 kilometers per hour (3 km/h), to express the distance d as a function of time t in hours, we use the formula:
d(t) = speed × time
Since we are given that the speed is 3 km/h, the function becomes:
d(t) = 3 × t
This linear equation means that for every hour t that the pedestrian walks, they will have covered a distance of 3 kilometers.