Mr. S is being monitored for asthma, so the doctor is having him record his flow rate over the course of a week, Mr. S's peak flow of air through his respiratory
system is estimated to be 642 L/min. Which of the following flow rates would
suggest he should seek immediate medical attention?

1)545 L/min (85% of peak flow)
2)449 L/min (70% of peak flow)
3)353 L/min (55% of peak flow)
4)256,1 L/min (40% of peak flow)