8 hours and 20 minutes = 8 + 20/60 hours = 81/3 hours = 8.33... recurring hours.
You write "six and a half hours" as 6.5 hours. Mathematically, that's the correct way to represent a number with a decimal point. So, there you have it - no need to complicate things!
4.15
4
You would write 11 cents as $0.11 or $.11 in decimal form.
2.25 hours.
3.416666 repeating hours
It is: 9 and 25/60 = 9.417 hours rounded to 3 decimal places
3 hours 30 minutes = 3.5 hours
3.25 hours
1 hour + 75 minutes = 2 hours 15 minutes... That's 2.25 hours as a decimal.
5.25 hours
It is: 3.333...recurring 3 which is the same as 3 and 1/3 hours
Oh, dude, it's like 4 hours and 20 minutes, right? So, you just divide 20 by 60 to get 0.33 hours, and then you add that to the 4 hours, giving you 4.33 hours in decimal form. Easy peasy, right?
1.1666 recurring hours.
25 minutes = 0.4167 hours
2 hours 10 minutes in decimal form is usually written as 2:10 or 2:10:00