How do I use excel to find an average time?

I swim and record my time for every 250m I swim. The time is recorded in excel in hh:mm:ss format. How do I find out what my average swim time is per 25 metres?

My spreadsheet looks like this:

Time Distance

Lap 1 00:07:05 250
Lap 2 00:07:17 250
Lap 3 00:07:21 250
Lap 4 00:07:23 250

Thanks for your help