6 and 1/2
2 hours.
21 hours
There are 16 hours from 4 am to 8 pm. 4 am to 4 pm is 12 hours, then 4 pm to 8 pm is another 4 hours.
It is seven hours from 9 AM to 4 PM.
6 hours.
3 hours.
3 hours.
2.5 hours
There are 16 hours from 9 PM to 1 PM the next day.
6 and 1/2
(8.5+24k) hours where k is an integer.
If one is am and the other is pm, there are 7 hours in this period. If they are both am or pm, there are 5 hours in this period.
There are seven hours between 730 am and 230 pm. 0.5 + 4 + 2.5 = 7 [1/2 hour to 8 then 4 hours to 12 and 2.5 hours to 2:30] or 14:30 - 7:30 = 7 [14:30 on 24 hour clock is 2:30pm]
12 Hours ! There are 12 hours in the AM and 12 hours in the PM !
12 hours
12 hours