Calculating fractions of hours from time date range

Hello friends,

I'm using sql server 2008 r2 and I have a table called attendance with the following fields

attendance_no    int
attendance_date    date
attendance_timein    time(7)
attendance_timeout    time(7)
emp_id    int   

and another table called employee with the following fields
emp_id int
emp_name  varchar(50)
emp_tel  varchar(50)

I need to calculate the total minutes worked as well as total hours worked for each employee with in a specified date range and I created the below query which working fine but it is not calculating the  fractions of hours, I mean when an employee works for example 7 and half hours, its showing just 7 hours instead of 7.5 hours.

SELECT a.attendance_date As 'Date',e.emp_id As 'ID',e.emp_name As 'Name',e.emp_tel As 'Telephone',left(a.attendance_timein,8)[Time in],left(a.attendance_timeout,8)[Time out],
   
   + CAST(DATEDIFF(second, attendance_timein, attendance_timeout) / 60 AS NVARCHAR(50)) As 'Total minutes',
   CAST(DATEDIFF(second,attendance_timein,attendance_timeout) / 60 /60 % 60 AS NVARCHAR(50)) As 'Total hours'

    from attendance a join employee e on e.emp_id=a.emp_id and a.attendance_date between '2014-11-06' and '2014-11-08'  and e.emp_tel='65098009'

I would appreciate any help about this.

Thanks in advance

Mohamoud