If you have a vital capacity of 4000 ml and can force out 3000 ml in 1 second, what's your fev1.0

FEV1 refers to the air that can be forced out in one second.  FEV1 is 3000 ml in 1 second.

FEV stands for Forced Expiration Volume. The number after the initials refer to the number of seconds. FEV1 is forced expiration volume in one second. FEV6 is forced expiration volume in six seconds.

I think that the vital capacity of 4000 ml is the FVC or Forced Vital Capacity. It is the total amount of air exhaled during the FEV test.