Question

The vital capacity, tidal volume, and inspiratory reserve volume of the lungs of a healthy individual are 4600 milliliters (mL), 500 mL, and 2500 mL, respectively. The expiratory reserve volume of the lungs of this individual is mL. (Round off to the nearest integer).

Hint:

Vital capacity is tidal volume plus inspiratory reserve volume plus expiratory reserve volume. Just subtract the two known volumes from vital capacity.

Answer 1

Correct Answer: 1600

Step 1: Picture vital capacity as one bar split into three pieces.
Imagine the full vital capacity, $VC = 4600$ mL, as a single bar. That bar is cut into three non overlapping pieces: tidal volume, inspiratory reserve volume, and expiratory reserve volume. Since the three pieces make up the whole bar with nothing left over, they must add to the total:
\[ TV + IRV + ERV = VC \]

Step 2: Add up the two known pieces first.
We know two of the three pieces: $TV = 500$ mL and $IRV = 2500$ mL.
\[ TV + IRV = 500 + 2500 = 3000 \text{ mL} \]

Step 3: Whatever is left of the bar is the missing piece.
\[ ERV = VC - (TV + IRV) = 4600 - 3000 \]
\[ ERV = 1600 \text{ mL} \]

Step 4: Confirm the split is complete.
Checking the three pieces against the whole: $500 + 2500 + 1600 = 4600$ mL, exactly equal to the stated vital capacity, so no volume is missing or double counted. \[ \boxed{1600 \text{ mL}} \]