A 2 kb linear fragment of DNA was digested with restriction enzyme "Q" and produced a 0. 9 kb fragment and a 1. 1 kb fragment. When the same 2 kb fragment was cut with restriction enzyme "P", it yielded 0. 5 kb, 0. 7 kb, and 0. 8 kb fragments. When the 2 kb fragment was cut with a mixture of the two enzymes, then fragments of 0. 2, 0. 5, 0. 6, and 0. 7 kb were produced. What is the order of the restriction sites on this DNA fragment?
