Final answer:
Bradley's hiking speed is 4 miles per hour, which represents the number of miles he hikes in an hour. Units are important to specify in mathematics to avoid ambiguity, and Bradley's speed is reasonable when compared to other known running and hiking speeds.
Step-by-step explanation:
Bradley hikes 12 miles in 3 hours. To find the rate of Bradley's hiking speed, we can use the formula: speed = distance ÷ time. Plugging the values into the formula, we get: speed = 12 miles ÷ 3 hours = 4 miles per hour. This expression describes the number of miles per hour Bradley hikes.
Understanding units is crucial in mathematics. Without specifying units, the meaning of a number can be ambiguous. For example, if someone says they walked 12 without specifying the unit, it could mean 12 miles, kilometers, or any other unit of distance. On the other hand, for Bradley's hike, since we are given both the distance and time, we can accurately determine his speed in miles per hour.
It's also important to check if the answer is reasonable. In Bradley's case, hiking 4 miles per hour is a reasonable speed for a hiker. It's neither too slow nor unreasonably fast. This can be contrasted with the data provided about runners, where some run at 7.5 miles per hour or less, and others at 7.5 miles per hour or more. Also, marathon runners might average speeds like 9.5 miles per hour, which is a different context from hiking.