A clock tower bell sounds to mark off every hour with the number of bells equal to the hour (three consecutive bells sound at three o'clock, etc). The last bell marks the exact beginning of the hour.
The sounding of the bells for six o'clocks starts at 30 seconds before six.
Assuming that the bells are always evenly and equally spaced in time, how long before noon must the sounding of the bells begin?
The bell will take precisely (11/5)*30 = 66 seconds to strike noon and, so he sounding of the bells must commence precisely 1 minute 6 seconds before noon.