In arteriosclerosis, fatty material called plaque gradually builds up on the walls of arteries, impeding the flow

Question:

In arteriosclerosis, fatty material called plaque gradually builds up on the walls of arteries, impeding the flow of blood, which, in turn, can lead to stroke and heart attacks. Consider a model in which the carotid artery is represented as a circular cylinder with cross-sectional radius R = 0.3 cm and length L. Suppose it is discovered that plaque 0.07 cm thick is distributed uniformly over the inner wall of the carotid artery of a particular patient. Use increments to estimate the percentage of the total volume of the artery that is blocked by plaque.