When the time indicated by the clock is 15 o'clock, start counting the number of revolutions of the minute hand. The minute hand rotates 1920 times, what is the time indicated by the clock.
当时钟指示的时刻是15时整时，开始计算分针旋转的周数．分针旋转了1920周，时钟指示的时刻是多少时．
<result>15</result>