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。 | 
