几道有待讨论的机经题!

florachu

1. 15*0.0001*0.00001=a*10的b次方，0.1＜a＜1，求b值。我算了三遍，答案选项里面没有，诡异。。。大家好好算算吧
2. 已知xy＞0，问x／y+y／x是否大于2？   （1）x不等于y      （2)x=1.1y   a+b大于等于2倍根号ab的条件是否是a,b分别大于等于0?
3. 一个数字，是由ABCD中的两个和1或者2组成的（就是两个字母和一个数字的组合呗），字母可重复。但是有个条件是字母必须在一起，数字不能放在中间。问有几个这样的组合。

4. Diagnosis of drivers who incurred fatal car accidents reveals that among those drivers under 50 with fatal accidents, 5% are diganosed to have P**(一种眼部疾病). This disease affects peripheral vision. However among entire population under 50, only 3% are diagnosed to be infected with P**. Therefore it is the P** disease that has led to drivers' fatal accidents. 应该是选weaken的吧

A. Many patients with P** in later stage cannot drive because their sights are seriously hurt.
B. Diagnosis of P** requires use of a kind of test. However it's unlikely that people under 50 will take this test.
C. Although P** is considered to happen more often among ppl over 50, some younger ppl, who are in their 30s and 40s, are also infected with it.
D. Except from impact on peripheral vision, P** does not have impacts on other vision abilities.