Question

Frank cross-country skis with friends on weekends. Today, the group skied a route that included a 16-mile stretch of flat terrain. During that portion of the route, the group maintained a constant speed of 8 miles per hour. The function D(t) represents the distance, in miles, the group had traveled after t hours of skiing at a speed of 8 miles per hour.
What is the domain of D(t)? And is it real or whole numbers?

Answer 1

They travel 16 miles at 8 mph, so time runs from 0 up to 16/8 = 2 hours. D(t)=8t for 0 ≤ t ≤ 2, so the domain is [0, 2]. The variable t is continuous (real numbers), not just whole numbers.