averaging interval values

Hi All,

I have a table with one varchar field that contains time
intervals.

Is there any way to average or sum those intervals in a table ?

Table name : test

field name : t2 (varchar(40))

it contains all intervals as below

t2

1:01:01
0:25:15
7:09:01
8:09:05

Is there any way to average or sum those above values using a
function?

i could not type cast the varchar(40) to interval type.

How to change the datatype of field from varchar to interval?

Thanks and Regards,
Praveen