题目
The ratio of the number of male and female workers in a company in 2002 was 3 : 4. The ratio of the number of male and female workers in 2003 was 10 : 7.
Quantity A
Percent increase in the number of males from 2002 to 2003
Quantity B
Percent increase in the number of females from 2002 to 2003
选项
C.The two quantities are equal.
D.The relationship cannot be determined from the information given.
解析
2002年一家公司男工和女工的人数比例是3:4。2003年男工和女工的人数比例是10:7。
数量A:2002年到2003年男性人数的百分比增长
数量B:2002年到2003年女性人数的百分比增长设2002年男工人数为\(3x\),女工人数为\(4x\)(\(x>0\))。设2003年男工人数为\(10y\),女工人数为\(7y\)(\(y > 0\))
由于人数的变化存在一定关联,所以有\(3x + k = 10y\)且\(4x + m=7y\),其中\(k\)是男性人数的增加量,\(m\)是女性人数的增加量
由\(3x + k=10y\)可得\(k = 10y - 3x\),男性人数的增长率为\(\frac{k}{3x}=\frac{10y - 3x}{3x}=\frac{10y}{3x}- 1\)
由\(4x+m = 7y\)可得\(m=7y - 4x\),女性人数的增长率为\(\frac{m}{4x}=\frac{7y - 4x}{4x}=\frac{7y}{4x}-1\)
要比较\(\frac{10y}{3x}-1\)和\(\frac{7y}{4x}-1\)的大小,只需比较\(\frac{10y}{3x}\)和\(\frac{7y}{4x}\)的大小
\(\frac{10y}{3x}\div\frac{7y}{4x}=\frac{10y}{3x}\times\frac{4x}{7y}=\frac{40}{21}>1\)
所以\(\frac{10y}{3x}>\frac{7y}{4x}\),即男性人数的增长率大于女性人数的增长率,所以数量A大于数量B
综上,答案是A 。