英文版61.IMMUNIZATION Suppose that during a nationwide program

英文版
61.IMMUNIZATION Suppose that during a nationwide program to immunize the population against a certain form of influenza,public health officials found that the cost of inoculating x% of
the population was approximately C(x)=150x/(200-x) million dollars.
a.What is the domain of the function
b.For what values of x does C(x) have a practical interpretation in this context?
c.What was the cost of inoculating the second 50% of the population?
d.What percentage of the population had been inoculated by the time 37.5 million dollars had been spent?
主要是翻译
另外 a 中的答案给的是 x不等于200 个人认为应该是0-100

免疫(工作)应该在全国范围的程序期间,让人们得到能够预防大多数流感(病毒)的疫苗,公众健康组织发现,给x%的人民接种花费的钱约为
C(x)=150x/(200-x)
a.函数C的 取值范围?是多少
b.在x的值中,C(x)在上下文中是否有实际的解释?(感觉不太通)
c.给50%人口接种的花费约为多少?
d.如果花费37.5百万刀,能给多少人接种?
不等于200是正确的
因为照这样计算,给200%的人口接种 花费为0
你觉得合适吗