单选题
A total of 774 doctorates in mathematics were granted to United States citizens by American universities in the 1972～1973 school year, and W of these doctorates were granted to women. The total of such doctorates in the 1986～1987 school year was 362, and ω of these were granted to women. If the number of doctorates in mathematics granted to female citizens of the United States by American universities decreased from the 1972～1973 school year to the 1986～1987 school year, was the decrease less than 10 percent?
(1)
(1)
【正确答案】
C
【答案解析】[解析] 该题也即问
是否小于10%。(1)不充分，因为(1)中未涉及ω的值，所以无法判断上面的算式是否小于10%，(2)也不充分，因为由(2)中能得到W-ω=5，而得不到
的值，所以也无法判断是否小于10%；(1)+(2)充分：
，因此
是否小于10%。(1)不充分，因为(1)中未涉及ω的值，所以无法判断上面的算式是否小于10%，(2)也不充分，因为由(2)中能得到W-ω=5，而得不到的值，所以也无法判断是否小于10%；(1)+(2)充分：，因此