Calculate time including IF column value

Question

I have the basic time value formula, but I am having two problems;

The first is with this Total Comp Time formula:

=TEXT([Start Time]-[End Time],"h:mm")

It does display the difference in time as hours and minutes 1:30 as shown in the image. I would prefer it to show 1.5 because when the time is being manually deducted as 1, .5, or .25 of an hour (Comp Time Taken ex.in the image .5) the calculated column Comp Time Left is not accurate.

The formula being used for Comp Time Left:

=TEXT([Total Comp Time]-[Comp Time Taken],"h:mm")

Part 2 of my problem is I only wanted Total Comp Time to appear only if the "Status" column says "Approved"

I started on this formula below, but I can't seem to get it to work:

=IF([Status]=Approved, TEXT([Start Time]-[End Time],"h:mm"), “0”)

Answer 1

=IF([Status]="Approved",LEFT((TEXT([End Time]-[Start Time],"hh:mm")),2)+(RIGHT((TEXT([End Time]-[Start Time],"hh:mm")),2)/60),"") (return as number with 2 decimal points)

Answer 2

To get the time as a fraction of an hour then you'd do ([Start Time]-[End Time]) * 24.

Start Time | End Time | In H:MM | In Fraction
------------------------------------------------
     14:00 |    14:05 |    0:05 |  0.083333333
     14:00 |    14:10 |    0:10 |  0.166666667
     14:00 |    14:15 |    0:15 |  0.25
     14:00 |    14:20 |    0:20 |  0.333333333
     14:00 |    14:25 |    0:25 |  0.416666667
     14:00 |    14:30 |    0:30 |  0.5
     14:00 |    14:45 |    0:45 |  0.75
     14:00 |    14:55 |    0:55 |  0.916666667
     14:00 |    15:00 |    1:00 |  1
     14:00 |    15:05 |    1:05 |  1.083333333
     14:00 |    15:30 |    1:30 |  1.5