In order to get an accurate measurement, you need to repeat the process for Anne's lower slice (image 5/9). Here are the steps you should follow:
(1) Trace the outline of the lungs,
(2) measure the area of that polygon (don't click elsewhere in the image, or you'll have to re-draw the polygon!),
(3) threshold the polygon,
(4) measure the thresholded area, and
(5) record your answers.

Anne's total lung area (TLA) is the sum of the upper lung area and the lower lung area. Her total dead air (TDA) is the sum of the areas of dead air in her upper and lower slices.

Which statement describes Anne's lung capacity the best?

Hint: To make your first polygon disappear when you move to the next image, just click anywhere outside the shape.

	Anne's total lung area (TLA) is approximately 9,500 pixels, and the total dead air area (TDA) is about 360 pixels.
	Anne's total lung area (TLA) is approximately 27,000 pixels, and the total dead air area (TDA) is about 750 pixels.
	Anne's total lung area (TLA) is approximately 27,000 pixels, and her total dead air area (TDA) is about 2,800 pixels.