A 20-year-old university student weighs 138 lb and had a birth weight of 6 lb. Prove that at some point in her life she was growing at a rate of 6.6 pounds per year.

Jenny, a healthy young woman, had a battery of tests during a physical for a new job. Her RBC count was at the higher end of the normal range at that time, but four weeks later it was substantially elevated beyond that. When asked if any circumstances had changed in her life, she admitted to taking up smoking. How might her new habit explain her higher RBC count?

A 32-year-old woman complains that she has been experiencing aching pains in the medial two fingers of both hands and that during such episodes, the fingers become blanched and then blue. Her history is taken, and it is noted that she is a heavy smoker. The physician advises her that she must stop smoking and states that he will not prescribe any medication until she has discontinued smoking for a month. What is this woman's problem, and why was she told to stop smoking?

A 75-year-old woman and her 9-year-old granddaughter were in a car accident in which both sustained trauma to the chest while seated next to each other. X-ray images showed that the grandmother had several fractured ribs, but her granddaughter had none. Explain these different findings.

Show that a cubic function (a third-degree polynomial) always has exactly one point of inflection. If its graph has three x-intercepts x1, x2 and x3, show that the x-coordinate of the inflection point is (x1+x2+x3)/3.