Hey @jeremie Convert your Duration field in the lookup to formatting as a number. This should automatically turn it into "Duration in Seconds". Create a new formula field "Duration in Minutes" that turns that duration in seconds into duration in minu...

Sorry, Kelly! Let's do it backwards. IF(Average>1, Average) should work!

You can solution this by rolling the field up, showing NaN, then creating a second field that is a IF formula, removing any items that are NaN. IF({Rollup-Field}="NaN", BLANK(), {Rollup-Field})