all right here is the answer
A long long time ago, on a train ride up to Rajouri where my dad was posted, he tricked me with this question.. then again I was a little kid back then and couldn't argue with him
It all depends on how you assume the clock is working - is the hammer that strikes the bell already spring loaded or not
The official answer was 9 seconds
The hammer is loaded ready to strike, it strikes at 3'o clock sharp and then for 2 successive load-and-strike it takes 3 seconds i.e. 1.5 seconds per strike
thus for 7'o clock it will strike at 7:00 sharp and the 6 successive load and strikes wil take 6*1.5 = 9 seconds (or (3600*4) + 9 seconds if you actually start counting the time from 3 o'clock)
But some might argue (which I should have done) that the hammer is in the non load position and thus does not strike at 3:00 sharp. Instaed it takes 3 seconds for 3 load-and-strikes and thus 1 second per load-and-strike - in this instance 7 seconds (or 3600*4 + 7 seconds) to strike 7'o clock
peace be with all