I think you are confusing decimals with time values, a time value like 9:30 in Excel is not the same as 9.3 hours.

If you type in the time values for each day, e.g. in A1:A5 [in another worksheet] type in these time values (with colons)

3:17
9:30
9:30
9:30
2:40

...and use a sum function in A6, i.e.

=SUM(A1:A5)

make sure that A6 is formatted as [h]:mm and result should be 34:27