Sum if.. it think?


I have a column of cells that may contain either a 1 or 2 or.5

I need to add the column together and get a 1 to equal 15min, 2 to equal 25min and the .5 to equal 7.5 minutes.

I need the total minutes at the end of the column.

I am unable to add any extra rows to the spreadsheet.

Can anyone help?