Answer: The required sprinter's unit rate is 31 feet per second.
Step-by-step explanation: Given that a sprinter can run 279 feet in 9 seconds.
We are to find the sprinter's unit rate of feet per second.
We will be using the UNITARY method to solve the given problem.
According to the given information, we have
In 9 second, distance run by the sprinter = 279 feet.
Therefore, in 1 second, the distance run by sprinter will be
Thus, the required sprinter's unit rate is 31 feet per second.