Final answer:
The second person will reach the end of the trail first, as they will take 2.4 hours compared to the first person's 3 hours.
Step-by-step explanation:
To determine who will reach the end of the trail first, we need to calculate the time it takes for each person to reach the end of the trail.
For the first person:
Distance = 12 miles
Speed = 4 mph
Time = Distance / Speed = 12 miles / 4 mph = 3 hours
For the second person:
Distance = 12 miles - 3 miles = 9 miles
Speed = 3.75 mph
Time = Distance / Speed = 9 miles / 3.75 mph = 2.4 hours
Therefore, the second person will reach the end of the trail first, as they will take 2.4 hours compared to the first person's 3 hours.