215. the number of M men and the number of W women were selected to be members of one club last year. If all of the members are still in the club. Whether there is higher percentage of women joining the club this year?
1) M/2 + X = W/2 + X X is constant
2) W> M （C）
216. rounded to 10,000. X = 140,000; Y= 80,000. What is X+Y rounded to 10,000
1) actual numbers of X and Y are within 2% of 140,000 and 80,000, respectively.
2) X rounds up and Y rounds down (not sure which one rounds up which one rounds down)
217. 1 H2 和O2 在空气中各 有20000问它们的比例最多是多少？
1）不少于30000
2）H2 的比例是O2 的二倍 | 
