At six o’clock the wall clock struck 6 times. Checking with my watch, I noticed that the time between the first and last strokes was 30 seconds. How long will the clock take to strike 12 at midnight?
When the clock struck six, there were only 5 intervals between strokes, and each interval was 6 (30/5) seconds. Between the first and twelfth strokes there will be 11 intervals of 6 seconds each; therefore, 12 strokes will take 66 seconds.