Question 1099709
There are two answers.
If you're looking for the duration of the clock striking itself, since it takes 30 seconds to strike 6 times,
 it would take twice as long to strike twice as many times. So it would take 60 seconds to strike 12. 
The second answer would be that since it strikes at 6, then there are 6 hours until it strikes 12 o'clock. 
So in terms of elapsed time it would take the 6 hours plus the 60 seconds to strike 12. So that answer would be 361 minutes.