| Q30:
The percentage of households with an annual income of more than $40,000 is higher in
Merton county than in any other county. However, the percentage of households with an
annual income of $60,000 or more is highest in Sommer county.
If the statements above are true, which of the following can properly be concluded on the
basis of them?
A. No household in Merton county has an annual income of $60,000 or more.
B. Some households in Merton county have an annual income between $40,000 and
$60,000.
C. The number of households with an annual income of more than $40,000 is greater
in Merton than in Sommer county.
D. Average annual household income is higher in Sommer than in Merton county.
E. The percentage of households with an annual income of $80,000 is higher in
Sommer than in Merton county.
标准答案为Ｅ，我选的Ｂ。
因为设M市40000-60000为Ａ1,60000以上为Ｂ１，总人口为Ｃ１，S市相应A2, B2和Ｃ２，则有
（A1+B1)/C1>(A2+B2)/C2, B1/C1<B2/C2, 可推出A1/c1>A2/c2，同时A1/B1不能为０，否则第一个不等式就不成立了。而Ｅ却推不出来，请教各位。 | 
