Answer:
r(n) = 1000·(2/5)^n
Step-by-step explanation:
Since the tortoise travels 3/5 the remaining distance, the remaining distance at the end of the day is 2/5 of what it was at the beginning of the day. So, the function can be modeled by an exponential with a "growth" factor of 2/5:
r(n) = 1000·(2/5)^n
where r(n) is the number of remaining feet after n days of travel.
