Understanding time (minutes:seconds)

When I export a report to excel I get a column of 1:30, :45, 2:10. I am trying to get excel to understand that it's a minute and 30 seconds, 45 seconds and 2 minutes and 10 seconds. I am trying to get an average of the times.

Thank you.

Because my imported data does not include a zero ( :30 vs 0:30 ) the computer does not recognize it as a time. Is there a way to make excel comprehend that :30 is a time? Once it is turned in to a decimal, how do convert it back to a time? I don't care about the time of day ( I need :30, not 12:30 or 30:00 )

How about if A1 contains :30 then B1: =--(0&A1) Format as: hh:mm