174. In 1987 sinusitis was the most common chronic medical condition in the United States, followed by arthritis
and high blood pressure, in that order.
The incidence rates for both arthritis and high blood pressure increase with age, but the incidence rate for
sinusitis is the same for people of all ages.
The average age of the United States population will increase between 1987 and 2000.
Which of the following conclusions can be most properly drawn about chronic medical conditions in the
United States from the information given above?
(A) Sinusitis will be more common than either arthritis or high blood pressure in 2000.
(B) Arthritis will be the most common chronic medical condition in 2000.
(C) The average age of people suffering from sinusitis will increase between 1987 and 2000.
(D) Fewer people will suffer from sinusitis in 2000 than suffered from it in 1987.
(E) A majority of the population will suffer from at least one of the medical conditions mentioned above by the
year 2000.
Given that the incidence rate for sinusitis is the same for people of all ages, and that the average age of the
population will increase, if follows that the average age of people suffering from sinusitis will increase. Therefore,
C is the best answer.
Although it follows that sinusitis will become less common relative to arthritis and high blood pressure, nothing can be concluded about the exact ranking of the three diseases, so choices A and B are ruled out. Just because sinusitis will become relatively less common, one cannot conclude that it will become absolutely less common (choice D). Lacking information about levels of incidence of the diseases, one cannot conclude what proportion of the population has at least one of them (choice E).
这道题我做对了。
但是，我怎么没看出来文章中提到sinusitis will become less common了呢？
请大家指教！谢谢！ | 
