Answer:
6.87022901%
Explanation:
He measured 14 out of 13.1 inches. There is a difference of 0.9 inches when u subtract. He miscalculated by 0.9 out of 13.1. In a calculator you divide .9 by 13.1 you get 0.0687022901. Multiply by 100 to get the percent and round it to your desired decimal place.