Forced Vital Capacity FVC is the volume of air a person can

Forced Vital Capacity (FVC) is the volume of air a person can expel in 6 seconds. It is a standard measure of pulmonary function. Suppose a child is considered to have normal lung capacity if the child’s standardized Forced Vital Capacity (FVC) is within 1.25 standard deviations of the mean. What proportion of children is within the normal range of lung capacity as measured by FVC?