Suppose you want to cut 15 identical boards of length 6 feet. The procedure is to measure and cut the first​ board, then use the first board to measure and cut the second​ board, then use the second board to measure and cut the third​ board, and so on. What are the possible lengths of the 15th board​ if, each time you cut a​ board, there is a maximum error of 0.7​%?