A swimming pool is open for 7\dfrac127 2 1 7, start fraction, 1, divided by, 2, end fraction hours during a day. The pool
keeps one lifeguard on duty at a time, and each lifeguard's shift is 1\dfrac121 2 1 1, start fraction, 1, divided by, 2, end fraction hours long. How many shifts are there per day?
