The cell format is actually Time13:30

"Pete" wrote:

Although these may look like minutes and seconds, I think Excel has
taken them as hours, minutes and seconds and is just displaying [h]:mm.
Click on one of the cells and check the format with Format | Cells |
Number (tab).

If this is the case, then in a blank column enter the formula:

=A1/60, assuming your times are in column A, and format as [m]:ss. Copy
this down.

You can fix the values using <copy with Edit | Paste Special | Values
| OK, and you can also paste the fixed values to over-write the
original values. Hopefully, your SUM and AVERAGE formulae will work
after this.

Hope this helps.

Pete