Final answer:
Riley is cycling at a rate of approximately 30.8 feet per second when converting from 21 miles per hour.
Step-by-step explanation:
To convert Riley's cycling rate from miles per hour to feet per second, we need to know the conversion factors between these units. There are 5,280 feet in a mile, and there are 3,600 seconds in an hour. Using these conversion factors, we can calculate the rate in feet per second as follows:
Rate in feet per second = (Rate in miles per hour) × (Number of feet in a mile) / (Number of seconds in an hour)
Substituting the known values:
Rate in feet per second = (21 miles/hour) × (5,280 feet/mile) / (3,600 seconds/hour)
Now, let's perform the calculation:
Rate in feet per second = 21 × 5,280 / 3,600
Rate in feet per second = 30.8 feet/second (rounded to one decimal place)
Therefore, Riley is cycling at a rate of approximately 30.8 feet per second.