Final answer:
David hikes at a speed of 4 miles per hour, and after hiking for 3 and 1/2 hours, he will have hiked 14 miles. The answer has been checked and is reasonable.
Step-by-step explanation:
To calculate the distance David will hike in 3 and 1/2 hours, we first need to establish his hiking speed. We know David hikes 2 miles in 1/2 hour. From this, we can calculate that David's hiking speed is 4 miles per hour (since 2 miles divided by 1/2 hour equals 4 miles per hour).
Next, we can find out how many miles David will hike in 3 and 1/2 hours by multiplying his hiking speed by the total hiking time:
Distance = Speed × Time
Distance = 4 miles/hour × 3.5 hours
Distance = 14 miles
Therefore, David will have hiked 14 miles after 3 and 1/2 hours.
Lastly, we check whether the answer is reasonable. Given that a constant hiking speed is maintained, the calculated distance makes sense for that time period.