Knock five times at five o'clock, with four intervals lasting six seconds. It can be seen that each interval lasts 1.5 seconds. The time required to knock 9 times at 9 o'clock confirms the above calculation.

Whenever you knock on the door, the interval is always 1 less than hours. The total interval for the clock to strike within 24 hours is:

2*(0+ 1+2+3+4+5+6+7+8+9+ 10+ 1 1)= 132

So the time required to ring the bell is:

1.5 *132 =198 (seconds)