5.5 hours. (30 minutes is half an hour, expressed as 0.5hrs, or every 0.1hrs is 6.0min.)
It is: 4.5 hours
2.5
2.5 hours
It is 1.5 hours
Everything before the decimal is hours. Everything behind multiplies with 60. 3 hours and (0.5x60=30) 30 minutes.
III hours, XXX minutes
First you divide by 60 to find the hours. In this case, you do 1800/60 and get 30. There is no decimal part or remainder and so there will be no minutes. Therefore, in 1,800 minutes, there is exactly 30 hours.
7 h. 30 min.
450 minutes.
7 Hours, 30 minutes. 7 1/2 hours. Top one?
Take just the decimal, and multiply it by 60. So if you have 3.5 hours, you do 0.5 x 60 to get 30 minutes. If you have 6.48 hours, you do 0.48 x 60 to get 28.8 minutes, for which you can do the same thing with the decimal to get seconds (0.8 x 60 = 48 seconds)