Let's go through the problem. Katie originally has 8 feet of ribbon. If she cuts off 3 feet of ribbon she has 5 feet of ribbon left. And since she cuts the 5 feet of ribbon into 8 pieces all you need to do is divide 5 by 8, which is 0.625 or 5/8.
The length of each shorter piece of ribbon is 5/8 or 0.625 feet.